635 lines
536 KiB
HTML
635 lines
536 KiB
HTML
|
<!DOCTYPE html>
|
|||
|
|
<html lang="zh"><head><title>数据库操作</title><meta charset="utf-8"/><link rel="preconnect" href="https://fonts.googleapis.com"/><link rel="preconnect" href="https://fonts.gstatic.com"/><link rel="stylesheet" href="https://fonts.googleapis.com/css2?family=IBM Plex Mono&family=Noto Serif Simplified Chinese:wght@400;700&family=Source Sans Pro:ital,wght@0,400;0,600;1,400;1,600&display=swap"/><meta name="viewport" content="width=device-width, initial-scale=1.0"/><meta property="og:title" content="数据库操作"/><meta property="og:description" content="Python DB-API 2.0 规范是一个重要的标准，它为 Python 程序与数据库间的交互提供了一致的接口。这个规范的目标是简化数据库编程，同时保持足够的灵活性来支持不同的数据库系统。."/><meta property="og:image" content="https://wiki.7wate.com/static/og-image.png"/><meta property="og:width" content="1200"/><meta property="og:height" content="675"/><link rel="icon" href="../../../../static/icon.png"/><meta name="description" content="Python DB-API 2.0 规范是一个重要的标准，它为 Python 程序与数据库间的交互提供了一致的接口。这个规范的目标是简化数据库编程，同时保持足够的灵活性来支持不同的数据库系统。."/><meta name="generator" content="Quartz"/><link href="../../../../index.css" rel="stylesheet" type="text/css" spa-preserve/><link href="https://cdnjs.cloudflare.com/ajax/libs/KaTeX/0.16.9/katex.min.css" rel="stylesheet" type="text/css" spa-preserve/><script src="../../../../prescript.js" type="application/javascript" spa-preserve></script><script type="application/javascript" spa-preserve>const fetchData = fetch("../../../../static/contentIndex.json").then(data => data.json())</script></head><body data-slug="Technology/ProgrammingLanguage/Python/进阶/数据库操作"><div id="quartz-root" class="page"><div id="quartz-body"><div class="left sidebar"><h2 class="page-title"><a href="../../../..">🪴 X·Eden</a></h2><div class="spacer mobile-only"></div><div class="search"><button class="search-button" id="search-button"><p>搜索</p><svg role="img" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 19.9 19.7"><title>Search</title><g class="search-path" fill="none"><path stroke-linecap="square" d="M18.5 18.3l-5.4-5.4"></path><circle cx="8" cy="8" r="7"></circle></g></svg></button><div id="search-container"><div id="search-space"><input autocomplete="off" id="search-bar" name="search" type="text" aria-label="搜索些什么" placeholder="搜索些什么"/><div id="search-layout" data-preview="true"></div></div></div></div><button class="darkmode" id="darkmode"><svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" version="1.1" id="dayIcon" x="0px" y="0px" viewBox="0 0 35 35" style="enable-background:new 0 0 35 35" xml:space="preserve" aria-label="暗色模式"><title>暗色模式</title><path d="M6,17.5C6,16.672,5.328,16,4.5,16h-3C0.672,16,0,16.672,0,17.5 S0.672,19,1.5,19h3C5.328,19,6,18.328,6,17.5z M7.5,26c-0.414,0-0.789,0.168-1.061,0.439l-2,2C4.168,28.711,4,29.086,4,29.5 C4,30.328,4.671,31,5.5,31c0.414,0,0.789-0.168,1.06-0.44l2-2C8.832,28.289,9,27.914,9,27.5C9,26.672,8.329,26,7.5,26z M17.5,6 C18.329,6,19,5.328,19,4.5v-3C19,0.672,18.329,0,17.5,0S16,0.672,16,1.5v3C16,5.328,16.671,6,17.5,6z M27.5,9 c0.414,0,0.789-0.168,1.06-0.439l2-2C30.832,6.289,31,5.914,31,5.5C31,4.672,30.329,4,29.5,4c-0.414,0-0.789,0.168-1.061,0.44 l-2,2C26.168,6.711,26,7.086,26,7.5C26,8.328,26.671,9,27.5,9z M6.439,8.561C6.711,8.832,7.086,9,7.5,9C8.328,9,9,8.328,9,7.5 c0-0.414-0.168-0.789-0.439-1.061l-2-2C6.289,4.168,5.914,4,5.5,4C4.672,4,4,4.672,4,5.5c0,0.414,0.168,0.789,0.439,1.06 L6.439,8.561z M33.5,16h-3c-0.828,0-1.5,0.672-1.5,1.5s0.672,1.5,1.5,1.5h3c0.828,0,1.5-0.672,1.5-1.5S34.328,16,33.5,16z M28.561,26.439C28.289,26.168,27.914,26,27.5,26c-0.828,0-1.5,0.672-1.5,1.5c0,0.414,0.168,0.789,0.439,1.06l2,2 C28.711,30.832,29.086,31,29.5,31c0.828,0,1.5-0.672,1.5-1.5c0-0.414-0.168-0.789-0.439-1.061L28.561,26.439z M17.5,29
|
|||
|
|
<p>**Python DB-API 2.0 规范是一个重要的标准，它为 Python 程序与数据库间的交互提供了一致的接口。**这个规范的目标是简化数据库编程，同时保持足够的灵活性来支持不同的数据库系统。</p>
|
|||
|
|
<p>DB-API 2.0 规范定义在 Python 标准库的 <a href="https://peps.python.org/pep-0249/" class="external">PEP 249<svg aria-hidden="true" class="external-icon" viewBox="0 0 512 512"><path d="M320 0H288V64h32 82.7L201.4 265.4 178.7 288 224 333.3l22.6-22.6L448 109.3V192v32h64V192 32 0H480 320zM32 32H0V64 480v32H32 456h32V480 352 320H424v32 96H64V96h96 32V32H160 32z"></path></svg></a> 文档中。它规定了数据库驱动（或数据库模块）应遵循的接口标准，以便程序员可以使用一致的编程风格来访问不同的数据库系统。</p>
|
|||
|
|
<h3 id="核心组件">核心组件<a role="anchor" aria-hidden="true" tabindex="-1" data-no-popover="true" href="#核心组件" class="internal"><svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path><path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path></svg></a></h3>
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
<div class="table-container"><table><thead><tr><th>组件</th><th>描述</th><th>关键方法或属性</th></tr></thead><tbody><tr><td><strong>连接对象（Connection）</strong></td><td>代表数据库的连接。</td><td>- <code>connect()</code>: 连接数据库。<br/>- <code>commit()</code>: 提交当前事务。<br/>- <code>rollback()</code>: 回滚当前事务。<br/>- <code>close()</code>: 关闭连接。</td></tr><tr><td><strong>游标对象（Cursor）</strong></td><td>用于执行查询和获取结果。</td><td>- <code>execute(sql, [parameters])</code>: 执行 SQL 语句。<br/>- <code>executemany(sql, seq_of_parameters)</code>: 执行相同的 SQL 语句多次。<br/>- <code>fetchone()</code>: 获取结果集的下一行。<br/>- <code>fetchmany(size)</code>: 获取结果集的下几行。<br/>- <code>fetchall()</code>: 获取结果集中的所有行。<br/>- <code>close()</code>: 关闭游标对象。</td></tr></tbody></table></div>
|
|||
|
|
<h3 id="标准方法">标准方法<a role="anchor" aria-hidden="true" tabindex="-1" data-no-popover="true" href="#标准方法" class="internal"><svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path><path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path></svg></a></h3>
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
<div class="table-container"><table><thead><tr><th>方法类型</th><th>方法名</th><th>描述</th></tr></thead><tbody><tr><td><strong>连接方法</strong></td><td><code>connect()</code></td><td>连接到数据库。</td></tr><tr><td></td><td><code>commit()</code></td><td>提交当前的事务。</td></tr><tr><td></td><td><code>rollback()</code></td><td>回滚当前的事务。</td></tr><tr><td></td><td><code>close()</code></td><td>关闭数据库连接。</td></tr><tr><td><strong>游标方法</strong></td><td><code>execute(sql, [parameters])</code></td><td>执行一个 SQL 语句。</td></tr><tr><td></td><td><code>executemany(sql, seq_of_parameters)</code></td><td>执行相同的 SQL 语句多次。</td></tr><tr><td></td><td><code>fetchone()</code></td><td>从结果集中获取下一行。</td></tr><tr><td></td><td><code>fetchmany(size)</code></td><td>从结果集中获取多行。</td></tr><tr><td></td><td><code>fetchall()</code></td><td>获取结果集中的所有行。</td></tr><tr><td></td><td><code>close()</code></td><td>关闭游标对象。</td></tr></tbody></table></div>
|
|||
|
|
<h3 id="标准异常">标准异常<a role="anchor" aria-hidden="true" tabindex="-1" data-no-popover="true" href="#标准异常" class="internal"><svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path><path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path></svg></a></h3>
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
<div class="table-container"><table><thead><tr><th>异常类别</th><th>描述</th></tr></thead><tbody><tr><td><code>Warning</code></td><td>警告类的基类，用于非致命性问题的提示。</td></tr><tr><td><code>Error</code></td><td>与数据库相关错误的基类。如果未指定具体的异常，则抛出这个错误。</td></tr><tr><td><code>InterfaceError</code></td><td>与数据库接口（而非数据库本身）相关的错误。</td></tr><tr><td><code>DatabaseError</code></td><td>数据库操作过程中发生的错误的基类。</td></tr><tr><td><code>DataError</code></td><td>数据异常，比如数值溢出、数据类型不匹配等。</td></tr><tr><td><code>OperationalError</code></td><td>数据库操作中的内部错误，如连接问题、内存分配问题等。</td></tr><tr><td><code>IntegrityError</code></td><td>数据完整性相关的错误，如外键违反等。</td></tr><tr><td><code>InternalError</code></td><td>数据库内部错误，如游标无效、事务同步失效等。</td></tr><tr><td><code>ProgrammingError</code></td><td>程序错误，如表找不到、SQL 语句语法错误等。</td></tr><tr><td><code>NotSupportedError</code></td><td>当尝试使用数据库不支持的功能或 API 时抛出的错误。</td></tr></tbody></table></div>
|
|||
|
|
<h2 id="python-数据库操作">Python 数据库操作<a role="anchor" aria-hidden="true" tabindex="-1" data-no-popover="true" href="#python-数据库操作" class="internal"><svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path><path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path></svg></a></h2>
|
|||
|
|
<p>首先，需要安装对应数据库的 Python 库，例如，如果是使用 MySQL，可以安装 <code>mysql-connector-python</code>。然后，可以使用如下代码连接到数据库并执行简单的 SQL 语句：</p>
|
|||
|
|
<figure data-rehype-pretty-code-figure><pre tabindex="0" data-language="python" data-theme="github-light github-dark"><code data-language="python" data-theme="github-light github-dark" style="display:grid;"><span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">import</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> sqlite3</span></span>
|
|||
|
|
<span data-line> </span>
|
|||
|
|
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">try</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">:</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"> # 连接到 SQLite 数据库</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"> # 如果文件不存在，会自动创建</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> conn </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> sqlite3.connect(</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">'example.db'</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">)</span></span>
|
|||
|
|
<span data-line> </span>
|
|||
|
|
<span data-line><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"> # 创建一个游标对象，用于执行 SQL 命令</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> cursor </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> conn.cursor()</span></span>
|
|||
|
|
<span data-line> </span>
|
|||
|
|
<span data-line><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"> # 创建一个新表</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"> # IF NOT EXISTS 用于避免在表已存在时产生错误</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> cursor.execute(</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">'''</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> CREATE TABLE IF NOT EXISTS stocks</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> (date text, trans text, symbol text, qty real, price real)</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> '''</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">)</span></span>
|
|||
|
|
<span data-line> </span>
|
|||
|
|
<span data-line><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"> # 插入一条记录</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> cursor.execute(</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">"INSERT INTO stocks VALUES ('2023-11-17','BUY','AAPL',100,35.14)"</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">)</span></span>
|
|||
|
|
<span data-line> </span>
|
|||
|
|
<span data-line><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"> # 提交当前事务</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> conn.commit()</span></span>
|
|||
|
|
<span data-line> </span>
|
|||
|
|
<span data-line><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"> # 查询数据</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> cursor.execute(</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">"SELECT * FROM stocks WHERE symbol = 'AAPL'"</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">)</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> print</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(cursor.fetchall())</span></span>
|
|||
|
|
<span data-line> </span>
|
|||
|
|
<span data-line><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># 捕获任何可能发生的异常</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">except</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> sqlite3.Error </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">as</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> e:</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> print</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">f</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">"数据库错误: </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">{</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">e</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">}</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">"</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">)</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">except</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> Exception</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> as</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> e:</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> print</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">f</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">"非数据库错误: </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">{</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">e</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">}</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">"</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">)</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">finally</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">:</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"> # 关闭游标</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> if</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> cursor:</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> cursor.close()</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"> # 关闭数据库连接</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> if</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> conn:</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> conn.close()</span></span>
|
|||
|
|
<span data-line> </span></code></pre></figure>
|
|||
|
|
<h3 id="连接connection">连接（Connection）<a role="anchor" aria-hidden="true" tabindex="-1" data-no-popover="true" href="#连接connection" class="internal"><svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path><path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path></svg></a></h3>
|
|||
|
|
<p>连接对象代表了 Python 应用程序和数据库之间的连接。通过这个连接，程序能够执行 SQL 命令、处理事务。</p>
|
|||
|
|
<h4 id="创建连接">创建连接<a role="anchor" aria-hidden="true" tabindex="-1" data-no-popover="true" href="#创建连接" class="internal"><svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path><path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path></svg></a></h4>
|
|||
|
|
<ul>
|
|||
|
|
<li>连接是通过调用特定数据库模块的 <code>connect()</code> 函数创建的。</li>
|
|||
|
|
<li>这个函数通常需要数据库特定的参数，如主机名、数据库名、用户名和密码。</li>
|
|||
|
|
</ul>
|
|||
|
|
<figure data-rehype-pretty-code-figure><pre tabindex="0" data-language="python" data-theme="github-light github-dark"><code data-language="python" data-theme="github-light github-dark" style="display:grid;"><span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">import</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> sqlite3</span></span>
|
|||
|
|
<span data-line> </span>
|
|||
|
|
<span data-line><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># 创建连接到 SQLite 数据库文件 'example.db'</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">conn </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> sqlite3.connect(</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">'example.db'</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">)</span></span></code></pre></figure>
|
|||
|
|
<h4 id="关键特性和方法">关键特性和方法<a role="anchor" aria-hidden="true" tabindex="-1" data-no-popover="true" href="#关键特性和方法" class="internal"><svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path><path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path></svg></a></h4>
|
|||
|
|
<ol>
|
|||
|
|
<li><strong>事务处理</strong>：
|
|||
|
|
<ul>
|
|||
|
|
<li><code>commit()</code>: 提交当前事务。在执行如 INSERT、UPDATE、DELETE 等操作后，需要调用此方法以确保更改被保存。</li>
|
|||
|
|
<li><code>rollback()</code>: 回滚当前事务。在遇到错误或需要撤销更改时使用。</li>
|
|||
|
|
</ul>
|
|||
|
|
</li>
|
|||
|
|
<li><strong>连接管理</strong>：
|
|||
|
|
<ul>
|
|||
|
|
<li><code>close()</code>: 关闭连接。关闭后，连接对象和其下所有的游标将不可用。</li>
|
|||
|
|
</ul>
|
|||
|
|
</li>
|
|||
|
|
<li><strong>错误处理</strong>：
|
|||
|
|
<ul>
|
|||
|
|
<li>连接操作可能会抛出 DB-API 定义的异常，如 <code>InterfaceError</code> 或 <code>DatabaseError</code>。</li>
|
|||
|
|
</ul>
|
|||
|
|
</li>
|
|||
|
|
</ol>
|
|||
|
|
<figure data-rehype-pretty-code-figure><pre tabindex="0" data-language="python" data-theme="github-light github-dark"><code data-language="python" data-theme="github-light github-dark" style="display:grid;"><span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">try</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">:</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"> # 执行数据库操作</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> conn.commit() </span><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># 提交事务</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">except</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> Exception</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> as</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> e:</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> conn.rollback() </span><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># 回滚事务</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> raise</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> e</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">finally</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">:</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> conn.close() </span><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># 关闭连接</span></span></code></pre></figure>
|
|||
|
|
<p>Python 进行数据库操作务必管理好数据库连接的生命周期。使用完毕后应及时关闭，避免资源泄露。建议使用 Python 的上下文管理器（<code>with</code> 语句）可以自动管理连接的开启和关闭。</p>
|
|||
|
|
<h3 id="游标cursor">游标（Cursor）<a role="anchor" aria-hidden="true" tabindex="-1" data-no-popover="true" href="#游标cursor" class="internal"><svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path><path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path></svg></a></h3>
|
|||
|
|
<p>游标是通过连接对象创建的，用于执行 SQL 命令和处理查询结果。</p>
|
|||
|
|
<h4 id="创建游标">创建游标<a role="anchor" aria-hidden="true" tabindex="-1" data-no-popover="true" href="#创建游标" class="internal"><svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path><path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path></svg></a></h4>
|
|||
|
|
<ul>
|
|||
|
|
<li>通过连接对象的 <code>cursor()</code> 方法创建。</li>
|
|||
|
|
<li>可以创建多个游标，用于执行不同的数据库操作。</li>
|
|||
|
|
</ul>
|
|||
|
|
<figure data-rehype-pretty-code-figure><pre tabindex="0" data-language="python" data-theme="github-light github-dark"><code data-language="python" data-theme="github-light github-dark" style="display:grid;"><span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">cursor </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> conn.cursor() </span><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># 创建游标</span></span></code></pre></figure>
|
|||
|
|
<h4 id="关键特性和方法-1">关键特性和方法<a role="anchor" aria-hidden="true" tabindex="-1" data-no-popover="true" href="#关键特性和方法-1" class="internal"><svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path><path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path></svg></a></h4>
|
|||
|
|
<ol>
|
|||
|
|
<li><strong>执行 SQL 命令</strong>：
|
|||
|
|
<ul>
|
|||
|
|
<li><code>execute(sql, [parameters])</code>: 执行单个 SQL 命令。</li>
|
|||
|
|
<li><code>executemany(sql, seq_of_parameters)</code>: 执行相同 SQL 命令多次，但使用不同的参数。</li>
|
|||
|
|
</ul>
|
|||
|
|
</li>
|
|||
|
|
<li><strong>结果处理</strong>：
|
|||
|
|
<ul>
|
|||
|
|
<li><code>fetchone()</code>: 返回结果集的下一行。</li>
|
|||
|
|
<li><code>fetchmany(size)</code>: 返回结果集的下几行。</li>
|
|||
|
|
<li><code>fetchall()</code>: 返回结果集中的所有行。</li>
|
|||
|
|
</ul>
|
|||
|
|
</li>
|
|||
|
|
<li><strong>元数据获取</strong>：
|
|||
|
|
<ul>
|
|||
|
|
<li>游标对象提供了诸如 <code>description</code> 属性，可以用来获取查询结果的列信息。</li>
|
|||
|
|
</ul>
|
|||
|
|
</li>
|
|||
|
|
<li><strong>游标管理</strong>：
|
|||
|
|
<ul>
|
|||
|
|
<li><code>close()</code>: 关闭游标。关闭后，游标将不可用。</li>
|
|||
|
|
</ul>
|
|||
|
|
</li>
|
|||
|
|
</ol>
|
|||
|
|
<figure data-rehype-pretty-code-figure><pre tabindex="0" data-language="python" data-theme="github-light github-dark"><code data-language="python" data-theme="github-light github-dark" style="display:grid;"><span data-line><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># 执行 SQL 查询</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">cursor.execute(</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">'SELECT * FROM some_table'</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">)</span></span>
|
|||
|
|
<span data-line> </span>
|
|||
|
|
<span data-line><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># 获取查询结果</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">rows </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> cursor.fetchall() </span><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># 获取所有行</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">for</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> row </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">in</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> rows:</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> print</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(row)</span></span>
|
|||
|
|
<span data-line> </span>
|
|||
|
|
<span data-line><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># 关闭游标</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">cursor.close()</span></span></code></pre></figure>
|
|||
|
|
<p>为避免资源占用，执行完毕后应及时关闭游标。使用参数化查询而不是字符串拼接，以防止 SQL 注入攻击。</p>
|
|||
|
|
<h3 id="执行-sql-语句execute">执行 SQL 语句（execute）<a role="anchor" aria-hidden="true" tabindex="-1" data-no-popover="true" href="#执行-sql-语句execute" class="internal"><svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path><path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path></svg></a></h3>
|
|||
|
|
<p>在 Python 中，使用游标对象执行 SQL 语句并处理结果。</p>
|
|||
|
|
<ul>
|
|||
|
|
<li>使用游标对象的 <code>execute()</code> 方法执行 SQL 语句。</li>
|
|||
|
|
<li>对于查询操作（如 SELECT），结果可以通过游标提供的方法获取。</li>
|
|||
|
|
<li>对于非查询操作（如 INSERT、UPDATE、DELETE），结果通常是影响的行数。</li>
|
|||
|
|
</ul>
|
|||
|
|
<figure data-rehype-pretty-code-figure><pre tabindex="0" data-language="python" data-theme="github-light github-dark"><code data-language="python" data-theme="github-light github-dark" style="display:grid;"><span data-line><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># 执行一个查询</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">cursor.execute(</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">'SELECT * FROM some_table'</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">)</span></span>
|
|||
|
|
<span data-line> </span>
|
|||
|
|
<span data-line><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># 或者执行一个更新</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">cursor.execute(</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">'UPDATE some_table SET column = value WHERE condition'</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">)</span></span></code></pre></figure>
|
|||
|
|
<h3 id="处理结果">处理结果<a role="anchor" aria-hidden="true" tabindex="-1" data-no-popover="true" href="#处理结果" class="internal"><svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path><path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path></svg></a></h3>
|
|||
|
|
<ul>
|
|||
|
|
<li>使用 <code>fetchone()</code>、<code>fetchmany(size)</code> 或 <code>fetchall()</code> 方法获取查询结果。</li>
|
|||
|
|
<li><code>fetchone()</code> 返回单行，<code>fetchmany(size)</code> 返回指定数量的行，<code>fetchall()</code> 返回所有行。</li>
|
|||
|
|
</ul>
|
|||
|
|
<figure data-rehype-pretty-code-figure><pre tabindex="0" data-language="python" data-theme="github-light github-dark"><code data-language="python" data-theme="github-light github-dark" style="display:grid;"><span data-line><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># 执行查询</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">cursor.execute(</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">'SELECT * FROM some_table'</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">)</span></span>
|
|||
|
|
<span data-line> </span>
|
|||
|
|
<span data-line><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># 获取单行</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">row </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> cursor.fetchone()</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">print</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(row)</span></span>
|
|||
|
|
<span data-line> </span>
|
|||
|
|
<span data-line><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># 获取多行</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">rows </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> cursor.fetchmany(</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">5</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">)</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">for</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> row </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">in</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> rows:</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> print</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(row)</span></span>
|
|||
|
|
<span data-line> </span>
|
|||
|
|
<span data-line><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># 获取所有行</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">all_rows </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> cursor.fetchall()</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">for</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> row </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">in</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> all_rows:</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> print</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(row)</span></span></code></pre></figure>
|
|||
|
|
<h3 id="错误处理">错误处理<a role="anchor" aria-hidden="true" tabindex="-1" data-no-popover="true" href="#错误处理" class="internal"><svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path><path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path></svg></a></h3>
|
|||
|
|
<p>在 Python 数据库编程中，错误处理是必不可少的部分。常见的数据库错误包括连接错误、SQL 语法错误、数据类型不匹配等。合理的错误处理可以提高程序的健壮性和用户体验。</p>
|
|||
|
|
<ul>
|
|||
|
|
<li>使用 <code>try-except</code> 块捕获并处理数据库异常。</li>
|
|||
|
|
<li>利用 Python 的 DB-API 定义的异常类（如 <code>DatabaseError</code>，<code>IntegrityError</code> 等）来识别和响应特定的错误情况。</li>
|
|||
|
|
</ul>
|
|||
|
|
<figure data-rehype-pretty-code-figure><pre tabindex="0" data-language="python" data-theme="github-light github-dark"><code data-language="python" data-theme="github-light github-dark" style="display:grid;"><span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">try</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">:</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> conn.execute(</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">'SELECT * FROM non_existent_table'</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">)</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">except</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> sqlite3.DatabaseError </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">as</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> e:</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> print</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">"Database error occurred:"</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, e)</span></span></code></pre></figure>
|
|||
|
|
<h4 id="调试数据库应用">调试数据库应用<a role="anchor" aria-hidden="true" tabindex="-1" data-no-popover="true" href="#调试数据库应用" class="internal"><svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path><path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path></svg></a></h4>
|
|||
|
|
<ul>
|
|||
|
|
<li>使用日志记录重要的操作和异常信息。</li>
|
|||
|
|
<li>在开发阶段，打印或记录 SQL 语句和其参数，以便检查和调整。</li>
|
|||
|
|
<li>使用交互式 Python 环境（如 IPython 或 Jupyter Notebook）进行逐步执行和测试。</li>
|
|||
|
|
</ul>
|
|||
|
|
<h3 id="参数化查询">参数化查询<a role="anchor" aria-hidden="true" tabindex="-1" data-no-popover="true" href="#参数化查询" class="internal"><svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path><path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path></svg></a></h3>
|
|||
|
|
<p>参数化查询是一种编写 SQL 查询的方法，可以提高安全性和灵活性。</p>
|
|||
|
|
<h4 id="编写安全的-sql-查询以避免-sql-注入">编写安全的 SQL 查询以避免 SQL 注入<a role="anchor" aria-hidden="true" tabindex="-1" data-no-popover="true" href="#编写安全的-sql-查询以避免-sql-注入" class="internal"><svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path><path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path></svg></a></h4>
|
|||
|
|
<p>通过使用占位符而非直接拼接字符串来构建 SQL 语句，可以有效防止 SQL 注入攻击。</p>
|
|||
|
|
<figure data-rehype-pretty-code-figure><pre tabindex="0" data-language="python" data-theme="github-light github-dark"><code data-language="python" data-theme="github-light github-dark" style="display:grid;"><span data-line><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># 错误的做法：直接字符串拼接</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">unsafe_sql </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> "SELECT * FROM users WHERE name = '"</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> +</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> user_input </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">+</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> "'"</span></span>
|
|||
|
|
<span data-line> </span>
|
|||
|
|
<span data-line><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># 正确的做法：使用参数化查询</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">cursor.execute(</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">"SELECT * FROM users WHERE name = </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">%s</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">"</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, (user_input,))</span></span></code></pre></figure>
|
|||
|
|
<h4 id="使用参数而非字符串拼接">使用参数而非字符串拼接<a role="anchor" aria-hidden="true" tabindex="-1" data-no-popover="true" href="#使用参数而非字符串拼接" class="internal"><svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path><path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path></svg></a></h4>
|
|||
|
|
<p>在构建 SQL 语句时，应优先考虑使用参数化查询。</p>
|
|||
|
|
<figure data-rehype-pretty-code-figure><pre tabindex="0" data-language="python" data-theme="github-light github-dark"><code data-language="python" data-theme="github-light github-dark" style="display:grid;"><span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">user_id </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> 5</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">cursor.execute(</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">"SELECT * FROM users WHERE id = </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">%s</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">"</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, (user_id,))</span></span></code></pre></figure>
|
|||
|
|
<h3 id="事务管理">事务管理<a role="anchor" aria-hidden="true" tabindex="-1" data-no-popover="true" href="#事务管理" class="internal"><svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path><path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path></svg></a></h3>
|
|||
|
|
<h3 id="基本概念acid-特性">基本概念（ACID 特性）<a role="anchor" aria-hidden="true" tabindex="-1" data-no-popover="true" href="#基本概念acid-特性" class="internal"><svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path><path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path></svg></a></h3>
|
|||
|
|
<p>事务是数据库操作的基本单位，它应满足 ACID 特性，即原子性（Atomicity）、一致性（Consistency）、隔离性（Isolation）、持久性（Durability）。</p>
|
|||
|
|
<ul>
|
|||
|
|
<li><strong>原子性</strong>：确保所有操作要么全部完成，要么全部不执行。</li>
|
|||
|
|
<li><strong>一致性</strong>：事务完成时，数据必须处于一致状态。</li>
|
|||
|
|
<li><strong>隔离性</strong>：多个事务同时进行时，一个事务的操作不应影响其他事务。</li>
|
|||
|
|
<li><strong>持久性</strong>：一旦事务提交，其结果就永久保存在数据库中。</li>
|
|||
|
|
</ul>
|
|||
|
|
<h4 id="在-python-中进行事务控制">在 Python 中进行事务控制<a role="anchor" aria-hidden="true" tabindex="-1" data-no-popover="true" href="#在-python-中进行事务控制" class="internal"><svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path><path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path></svg></a></h4>
|
|||
|
|
<p>在 Python 中，事务控制通常由连接对象（Connection）来管理。使用 <code>commit()</code> 和 <code>rollback()</code> 方法来控制事务的提交和回滚。</p>
|
|||
|
|
<figure data-rehype-pretty-code-figure><pre tabindex="0" data-language="python" data-theme="github-light github-dark"><code data-language="python" data-theme="github-light github-dark" style="display:grid;"><span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">conn </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> sqlite3.connect(</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">'example.db'</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">)</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">try</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">:</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"> # 开始一个事务</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> conn.execute(</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">'INSERT INTO table_name VALUES (...)'</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">)</span></span>
|
|||
|
|
<span data-line> </span>
|
|||
|
|
<span data-line><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"> # 更多数据库操作...</span></span>
|
|||
|
|
<span data-line> </span>
|
|||
|
|
<span data-line><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"> # 提交事务</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> conn.commit()</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">except</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> Exception</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> as</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> e:</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"> # 出现错误，回滚事务</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> conn.rollback()</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> raise</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> e</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">finally</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">:</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"> # 关闭连接</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> conn.close()</span></span></code></pre></figure>
|
|||
|
|
<h3 id="数据库连接池">数据库连接池<a role="anchor" aria-hidden="true" tabindex="-1" data-no-popover="true" href="#数据库连接池" class="internal"><svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path><path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path></svg></a></h3>
|
|||
|
|
<h4 id="理解数据库连接池的概念">理解数据库连接池的概念<a role="anchor" aria-hidden="true" tabindex="-1" data-no-popover="true" href="#理解数据库连接池的概念" class="internal"><svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path><path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path></svg></a></h4>
|
|||
|
|
<p>数据库连接池是一种创建和管理数据库连接的技术，用于减少建立和关闭连接的开销。在高并发情况下，连接池可以显著提高性能。</p>
|
|||
|
|
<h4 id="使用连接池提高性能">使用连接池提高性能<a role="anchor" aria-hidden="true" tabindex="-1" data-no-popover="true" href="#使用连接池提高性能" class="internal"><svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path><path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path></svg></a></h4>
|
|||
|
|
<p>在 Python 中，可以使用第三方库（如 <code>sqlalchemy.pool</code>）来实现数据库连接池。连接池管理着一组连接，当需要时分配给请求者，使用完毕后返回池中。</p>
|
|||
|
|
<figure data-rehype-pretty-code-figure><pre tabindex="0" data-language="python" data-theme="github-light github-dark"><code data-language="python" data-theme="github-light github-dark" style="display:grid;"><span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">from</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> sqlalchemy.pool </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">import</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> QueuePool</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">from</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> sqlalchemy </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">import</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> create_engine</span></span>
|
|||
|
|
<span data-line> </span>
|
|||
|
|
<span data-line><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># 创建一个带连接池的引擎</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">engine </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> create_engine(</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">'postgresql://username:password@localhost/dbname'</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, </span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">poolclass</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">QueuePool)</span></span>
|
|||
|
|
<span data-line> </span>
|
|||
|
|
<span data-line><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># 使用连接</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">with</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> engine.connect() </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">as</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> connection:</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> result </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> connection.execute(</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">"SELECT * FROM table_name"</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">)</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> for</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> row </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">in</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> result:</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> print</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(row)</span></span></code></pre></figure>
|
|||
|
|
<h2 id="orm-工具">ORM 工具<a role="anchor" aria-hidden="true" tabindex="-1" data-no-popover="true" href="#orm-工具" class="internal"><svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path><path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path></svg></a></h2>
|
|||
|
|
<p>在 Python 中，对象关系映射（Object-Relational Mapping, ORM）是一种流行的技术，它允许开发者以对象的形式操作数据库，而无需编写 SQL 语句。ORM（Object-Relational Mapping）是一种<strong>将数据库表转换为程序中对象的技术</strong>，使开发者能够以面向对象的方式处理数据库。</p>
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
<div class="table-container"><table><thead><tr><th>ORM 库</th><th>简介</th><th>特点</th><th>适用场景</th></tr></thead><tbody><tr><td>Django ORM</td><td>Django 框架的一部分</td><td>无需编写 SQL，支持多数据库，丰富的查询构造器</td><td>Django 框架的 web 应用</td></tr><tr><td>SQLAlchemy</td><td>流行的独立 ORM 工具</td><td>灵活模型定义，强大查询，支持多数据库</td><td>适用于各种规模应用，特别是复杂数据库应用</td></tr><tr><td>Peewee</td><td>小巧但功能完整的 ORM 库</td><td>简单易用，学习曲线低</td><td>小型项目或简单 ORM 需求</td></tr><tr><td>Tortoise ORM</td><td>异步 ORM 库</td><td>支持异步操作，适合异步编程环境</td><td>需要高并发处理的现代 web 应用</td></tr><tr><td>Pony ORM</td><td>提供直观查询语言的 ORM 库</td><td>独特的查询语法，易于理解</td><td>寻求直观查询方式的开发者</td></tr></tbody></table></div>
|
|||
|
|
<h3 id="基本的-orm-操作">基本的 ORM 操作<a role="anchor" aria-hidden="true" tabindex="-1" data-no-popover="true" href="#基本的-orm-操作" class="internal"><svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path><path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path></svg></a></h3>
|
|||
|
|
<p>使用 ORM 工具时，开发者定义模型（即类），这些模型映射到数据库的表。在 Python 中，常见的 ORM 工具包括 SQLAlchemy 和 Django ORM。</p>
|
|||
|
|
<figure data-rehype-pretty-code-figure><pre tabindex="0" data-language="python" data-theme="github-light github-dark"><code data-language="python" data-theme="github-light github-dark" style="display:grid;"><span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">from</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> sqlalchemy </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">import</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> create_engine, Column, Integer, String</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">from</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> sqlalchemy.ext.declarative </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">import</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> declarative_base</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">from</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> sqlalchemy.orm </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">import</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> sessionmaker</span></span>
|
|||
|
|
<span data-line> </span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">Base </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> declarative_base()</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">engine </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> create_engine(</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">'sqlite:///example.db'</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">)</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">Session </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> sessionmaker(</span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">bind</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">engine)</span></span>
|
|||
|
|
<span data-line> </span>
|
|||
|
|
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">class</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> User</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">Base</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">):</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> __tablename__ </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> 'users'</span></span>
|
|||
|
|
<span data-line> </span>
|
|||
|
|
<span data-line><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> id</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> Column(Integer, </span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">primary_key</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">True</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">)</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> name </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> Column(String)</span></span>
|
|||
|
|
<span data-line> </span>
|
|||
|
|
<span data-line><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># 创建表</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">Base.metadata.create_all(engine)</span></span>
|
|||
|
|
<span data-line> </span>
|
|||
|
|
<span data-line><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># 使用会话进行数据库操作</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">session </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> Session()</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">new_user </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> User(</span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">name</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">'Alice'</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">)</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">session.add(new_user)</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">session.commit()</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">session.close()</span></span></code></pre></figure>
|
|||
|
|
<h2 id="项目实战">项目实战<a role="anchor" aria-hidden="true" tabindex="-1" data-no-popover="true" href="#项目实战" class="internal"><svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path><path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path></svg></a></h2>
|
|||
|
|
<p>为了将所学知识应用于实际，可以从开发一个简单的数据库应用开始。例如，创建一个图书管理系统，包括图书的添加、查询、更新和删除功能。</p>
|
|||
|
|
<figure data-rehype-pretty-code-figure><pre tabindex="0" data-language="python" data-theme="github-light github-dark"><code data-language="python" data-theme="github-light github-dark" style="display:grid;"><span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">import</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> sqlite3</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">from</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> sqlite3 </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">import</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> Error</span></span>
|
|||
|
|
<span data-line> </span>
|
|||
|
|
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">def</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> create_connection</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(db_file):</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> """ 创建一个数据库连接到 SQLite 数据库 """</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> conn </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> None</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> try</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">:</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> conn </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> sqlite3.connect(db_file)</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> return</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> conn</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> except</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> Error </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">as</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> e:</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> print</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(e)</span></span>
|
|||
|
|
<span data-line> </span>
|
|||
|
|
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> return</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> conn</span></span>
|
|||
|
|
<span data-line> </span>
|
|||
|
|
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">def</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> create_table</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(conn, create_table_sql):</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> """ 创建表 """</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> try</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">:</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> c </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> conn.cursor()</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> c.execute(create_table_sql)</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> except</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> Error </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">as</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> e:</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> print</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(e)</span></span>
|
|||
|
|
<span data-line> </span>
|
|||
|
|
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">def</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> main</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">():</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> database </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> r</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">"</span><span style="--shiki-light:#032F62;--shiki-dark:#DBEDFF;">pythonsqlite</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">.</span><span style="--shiki-light:#032F62;--shiki-dark:#DBEDFF;">db</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">"</span></span>
|
|||
|
|
<span data-line> </span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> sql_create_projects_table </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> """ CREATE TABLE IF NOT EXISTS projects (</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> id integer PRIMARY KEY,</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> name text NOT NULL,</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> begin_date text,</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> end_date text</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> ); """</span></span>
|
|||
|
|
<span data-line> </span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> sql_create_tasks_table </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> """CREATE TABLE IF NOT EXISTS tasks (</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> id integer PRIMARY KEY,</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> name text NOT NULL,</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> priority integer,</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> status_id integer NOT NULL,</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> project_id integer NOT NULL,</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> begin_date text NOT NULL,</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> end_date text NOT NULL,</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> FOREIGN KEY (project_id) REFERENCES projects (id)</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> );"""</span></span>
|
|||
|
|
<span data-line> </span>
|
|||
|
|
<span data-line><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"> # 创建一个数据库连接</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> conn </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> create_connection(database)</span></span>
|
|||
|
|
<span data-line> </span>
|
|||
|
|
<span data-line><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"> # 创建表</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> if</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> conn </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">is</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> not</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> None</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">:</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> create_table(conn, sql_create_projects_table)</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> create_table(conn, sql_create_tasks_table)</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> else</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">:</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> print</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">"无法创建数据库连接。"</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">)</span></span>
|
|||
|
|
<span data-line> </span>
|
|||
|
|
<span data-line><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"> # 插入数据</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> project </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> (</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">'Cool App with SQLite & Python'</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, </span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">'2023-01-01'</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, </span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">'2023-12-31'</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">)</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> project_id </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> insert_project(conn, project)</span></span>
|
|||
|
|
<span data-line> </span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> task_1 </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> (</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">'Analyze the requirements of the app'</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">1</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">1</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, project_id, </span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">'2023-01-01'</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, </span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">'2023-01-02'</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">)</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> task_2 </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> (</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">'Confirm with user about the top priorities'</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">1</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">1</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, project_id, </span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">'2023-01-03'</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, </span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">'2023-01-05'</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">)</span></span>
|
|||
|
|
<span data-line> </span>
|
|||
|
|
<span data-line><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"> # 插入任务</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> insert_task(conn, task_1)</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> insert_task(conn, task_2)</span></span>
|
|||
|
|
<span data-line> </span>
|
|||
|
|
<span data-line><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"> # 查询数据</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> print</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">"1. 查询项目:"</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">)</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> select_all_projects(conn)</span></span>
|
|||
|
|
<span data-line> </span>
|
|||
|
|
<span data-line><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> print</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">"2. 查询任务:"</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">)</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> select_all_tasks(conn)</span></span>
|
|||
|
|
<span data-line> </span>
|
|||
|
|
<span data-line><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"> # 更新数据</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> update_task(conn, (</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">2</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, </span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">'2023-01-04'</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">2</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">))</span></span>
|
|||
|
|
<span data-line> </span>
|
|||
|
|
<span data-line><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"> # 删除数据</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> delete_task(conn, </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">2</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">)</span></span>
|
|||
|
|
<span data-line> </span>
|
|||
|
|
<span data-line><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"> # 关闭连接</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> conn.close()</span></span>
|
|||
|
|
<span data-line> </span>
|
|||
|
|
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">def</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> insert_project</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(conn, project):</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> """</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> 创建一个新的项目</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> :param conn:</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> :param project:</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> :return: project id</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> """</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> sql </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> ''' INSERT INTO projects(name,begin_date,end_date)</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> VALUES(?,?,?) '''</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> cur </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> conn.cursor()</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> cur.execute(sql, project)</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> conn.commit()</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> return</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> cur.lastrowid</span></span>
|
|||
|
|
<span data-line> </span>
|
|||
|
|
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">def</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> insert_task</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(conn, task):</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> """</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> 创建一个新的任务</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> :param conn:</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> :param task:</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> :return:</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> """</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> sql </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> ''' INSERT INTO tasks(name,priority,status_id,project_id,begin_date,end_date)</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> VALUES(?,?,?,?,?,?) '''</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> cur </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> conn.cursor()</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> cur.execute(sql, task)</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> conn.commit()</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> return</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> cur.lastrowid</span></span>
|
|||
|
|
<span data-line> </span>
|
|||
|
|
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">def</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> select_all_projects</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(conn):</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> """</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> 查询所有项目</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> :param conn: the Connection object</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> :return:</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> """</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> cur </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> conn.cursor()</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> cur.execute(</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">"SELECT * FROM projects"</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">)</span></span>
|
|||
|
|
<span data-line> </span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> rows </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> cur.fetchall()</span></span>
|
|||
|
|
<span data-line> </span>
|
|||
|
|
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> for</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> row </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">in</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> rows:</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> print</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(row)</span></span>
|
|||
|
|
<span data-line> </span>
|
|||
|
|
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">def</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> select_all_tasks</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(conn):</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> """</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> 查询所有任务</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> :param conn: the Connection object</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> :return:</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> """</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> cur </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> conn.cursor()</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> cur.execute(</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">"SELECT * FROM tasks"</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">)</span></span>
|
|||
|
|
<span data-line> </span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> rows </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> cur.fetchall()</span></span>
|
|||
|
|
<span data-line> </span>
|
|||
|
|
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> for</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> row </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">in</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> rows:</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> print</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(row)</span></span>
|
|||
|
|
<span data-line> </span>
|
|||
|
|
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">def</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> update_task</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(conn, task):</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> """</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> 更新任务</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> :param conn:</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> :param task:</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> :return: project id</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> """</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> sql </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> ''' UPDATE tasks</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> SET priority = ? ,</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> end_date = ?</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> WHERE id = ?'''</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> cur </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> conn.cursor()</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> cur.execute(sql, task)</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> conn.commit()</span></span>
|
|||
|
|
<span data-line> </span>
|
|||
|
|
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">def</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> delete_task</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(conn, id):</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> """</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> 删除一个任务通过任务 id</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> :param conn: Connection to the SQLite database</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> :param id: id of the task</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> :return:</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> """</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> sql </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> 'DELETE FROM tasks WHERE id=?'</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> cur </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> conn.cursor()</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> cur.execute(sql, (</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">id</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">,))</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> conn.commit()</span></span>
|
|||
|
|
<span data-line> </span>
|
|||
|
|
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">if</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> __name__</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> ==</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> '__main__'</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">:</span></span>
|
|||
|
|
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> main()</span></span></code></pre></figure></article><hr/><div class="page-footer"></div></div><div class="right sidebar"><div class="graph"><h3>关系图谱</h3><div class="graph-outer"><div id="graph-container" data-cfg="{"drag":true,"zoom":true,"depth":1,"scale":1.1,"repelForce":0.5,"centerForce":0.3,"linkDistance":30,"fontSize":0.6,"opacityScale":1,"showTags":true,"removeTags":[],"focusOnHover":false}"></div><button id="global-graph-icon" aria-label="Global Graph"><svg version="1.1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" x="0px" y="0px" viewBox="0 0 55 55" fill="currentColor" xml:space="preserve"><path d="M49,0c-3.309,0-6,2.691-6,6c0,1.035,0.263,2.009,0.726,2.86l-9.829,9.829C32.542,17.634,30.846,17,29,17
|
|||
|
|
s-3.542,0.634-4.898,1.688l-7.669-7.669C16.785,10.424,17,9.74,17,9c0-2.206-1.794-4-4-4S9,6.794,9,9s1.794,4,4,4
|
|||
|
|
c0.74,0,1.424-0.215,2.019-0.567l7.669,7.669C21.634,21.458,21,23.154,21,25s0.634,3.542,1.688,4.897L10.024,42.562
|
|||
|
|
C8.958,41.595,7.549,41,6,41c-3.309,0-6,2.691-6,6s2.691,6,6,6s6-2.691,6-6c0-1.035-0.263-2.009-0.726-2.86l12.829-12.829
|
|||
|
|
c1.106,0.86,2.44,1.436,3.898,1.619v10.16c-2.833,0.478-5,2.942-5,5.91c0,3.309,2.691,6,6,6s6-2.691,6-6c0-2.967-2.167-5.431-5-5.91
|
|||
|
|
v-10.16c1.458-0.183,2.792-0.759,3.898-1.619l7.669,7.669C41.215,39.576,41,40.26,41,41c0,2.206,1.794,4,4,4s4-1.794,4-4
|
|||
|
|
s-1.794-4-4-4c-0.74,0-1.424,0.215-2.019,0.567l-7.669-7.669C36.366,28.542,37,26.846,37,25s-0.634-3.542-1.688-4.897l9.665-9.665
|
|||
|
|
C46.042,11.405,47.451,12,49,12c3.309,0,6-2.691,6-6S52.309,0,49,0z M11,9c0-1.103,0.897-2,2-2s2,0.897,2,2s-0.897,2-2,2
|
|||
|
|
S11,10.103,11,9z M6,51c-2.206,0-4-1.794-4-4s1.794-4,4-4s4,1.794,4,4S8.206,51,6,51z M33,49c0,2.206-1.794,4-4,4s-4-1.794-4-4
|
|||
|
|
s1.794-4,4-4S33,46.794,33,49z M29,31c-3.309,0-6-2.691-6-6s2.691-6,6-6s6,2.691,6,6S32.309,31,29,31z M47,41c0,1.103-0.897,2-2,2
|
|||
|
|
s-2-0.897-2-2s0.897-2,2-2S47,39.897,47,41z M49,10c-2.206,0-4-1.794-4-4s1.794-4,4-4s4,1.794,4,4S51.206,10,49,10z"></path></svg></button></div><div id="global-graph-outer"><div id="global-graph-container" data-cfg="{"drag":true,"zoom":true,"depth":-1,"scale":0.9,"repelForce":0.5,"centerForce":0.3,"linkDistance":30,"fontSize":0.6,"opacityScale":1,"showTags":true,"removeTags":[],"focusOnHover":true}"></div></div></div><div class="toc desktop-only"><button type="button" id="toc" class aria-controls="toc-content" aria-expanded="true"><h3>目录</h3><svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" class="fold"><polyline points="6 9 12 15 18 9"></polyline></svg></button><div id="toc-content" class><ul class="overflow"><li class="depth-0"><a href="#python-db-api-20-规范概述" data-for="python-db-api-20-规范概述">Python DB-API 2.0 规范概述</a></li><li class="depth-1"><a href="#核心组件" data-for="核心组件">核心组件</a></li><li class="depth-1"><a href="#标准方法" data-for="标准方法">标准方法</a></li><li class="depth-1"><a href="#标准异常" data-for="标准异常">标准异常</a></li><li class="depth-0"><a href="#python-数据库操作" data-for="python-数据库操作">Python 数据库操作</a></li><li class="depth-1"><a href="#连接connection" data-for="连接connection">连接（Connection）</a></li><li class="depth-1"><a href="#游标cursor" data-for="游标cursor">游标（Cursor）</a></li><li class="depth-1"><a href="#执行-sql-语句execute" data-for="执行-sql-语句execute">执行 SQL 语句（execute）</a></li><li class="depth-1"><a href="#处理结果" data-for="处理结果">处理结果</a></li><li class="depth-1"><a href="#错误处理" data-for="错误处理">错误处理</a></li><li class="depth-1"><a href="#参数化查询" data-for="参数化查询">参数化查询</a></li><li class="depth-1"><a href="#事务管理" data-for="事务管理">事务管理</a></li><li class="depth-1"><a href="#基本概念acid-特性" data-for="基本概念acid-特性">基本概念（ACID 特性）</a></li><li class="depth-1"><a href="#数据库连接池" data-for="数据库连接池">数据库连接池</a></li><li class="depth-0"><a href="#orm-工具" data-for="orm-工具">ORM 工具</a></li><li class="depth-1"><a href="#基本的-orm-操作" data-for="基本的-orm-操作">基本的 ORM 操作</a></li><li class="depth-0"><a href="#项目实战" data-for="项目实战">项目实战</a></li></ul></div></div><div class="explorer mobile-only"><button type="button" id="explorer" data-behavior="collapse" data-collapsed="collapsed" data-savestate="true" data-tree="[{"path":"Personal","collapsed":true},{"path":"Personal/Blog","collapsed":true},{"path":"Personal/Blog/2018","collapsed":true},{"path":"Personal/Blog/2020","collapsed":true},{"path":"Personal/Blog/2021","collapsed":true},{"path":"Personal/Blog/2022","collapsed":true},{"path":"Personal/Blog/2023","collapsed":true},{"path":"Personal/Blog/2024","collapsed":true},{"path":"Personal/Book","collapsed":true},{"path":"Personal/Book/个人成长","collapsed":true},{"path":"Personal/Book/医学健康","collapsed":true},{"path":"Personal/Book/历史","collapsed":true},{"path":"Personal/Book/哲学宗教","collapsed":true},{"path":"Personal/Book/心理","collapsed":true},{"path":"Personal/Book/政治军事","collapsed":true},{"path":
|
|||
|
|
</script><script type="module">
|
|||
|
|
let mermaidImport = undefined
|
|||
|
|
document.addEventListener('nav', async () => {
|
|||
|
|
if (document.querySelector("code.mermaid")) {
|
|||
|
|
mermaidImport ||= await import('https://cdnjs.cloudflare.com/ajax/libs/mermaid/10.7.0/mermaid.esm.min.mjs')
|
|||
|
|
const mermaid = mermaidImport.default
|
|||
|
|
const darkMode = document.documentElement.getAttribute('saved-theme') === 'dark'
|
|||
|
|
mermaid.initialize({
|
|||
|
|
startOnLoad: false,
|
|||
|
|
securityLevel: 'loose',
|
|||
|
|
theme: darkMode ? 'dark' : 'default'
|
|||
|
|
})
|
|||
|
|
|
|||
|
|
await mermaid.run({
|
|||
|
|
querySelector: '.mermaid'
|
|||
|
|
})
|
|||
|
|
}
|
|||
|
|
});
|
|||
|
|
</script><script src="https://cdnjs.cloudflare.com/ajax/libs/KaTeX/0.16.9/contrib/copy-tex.min.js" type="application/javascript"></script><script src="../../../../postscript.js" type="module"></script></html>
|