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<html lang="zh"><head><title>SQL必知必会（第5版）</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="SQL必知必会（第5版）"/><meta property="og:description" content="SQL是使用最为广泛的数据库语言，几乎所有重要的DBMS都支持SQL。本书是麻省理工学院、伊利诺伊大学等众多大学的参考教材，由浅入深地讲解了SQL的基本概念和语法，涉及数据的排序、过滤和分组，以及表、视图、联结、子查询、游标、存储过程和触发器等内容，实例丰富，便于查阅。与其他同类图书不同，本书没有过多阐述数据库基础理论，而是专门针对一线软件开发人员，直接从SQLSELECT开始，讲述实际工作环境中最常用和最必需的SQL知识，实用性极强。新版对书中的案例进行了全面的更新，并增加了章后挑战题，便于读者巩固所学知识。 ..."/><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="SQL是使用最为广泛的数据库语言，几乎所有重要的DBMS都支持SQL。本书是麻省理工学院、伊利诺伊大学等众多大学的参考教材，由浅入深地讲解了SQL的基本概念和语法，涉及数据的排序、过滤和分组，以及表、视图、联结、子查询、游标、存储过程和触发器等内容，实例丰富，便于查阅。与其他同类图书不同，本书没有过多阐述数据库基础理论，而是专门针对一线软件开发人员，直接从SQLSELECT开始，讲述实际工作环境中最常用和最必需的SQL知识，实用性极强。新版对书中的案例进行了全面的更新，并增加了章后挑战题，便于读者巩固所学知识。 ..."/><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="Personal/Book/计算机/SQL必知必会（第5版）"><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-2,2C4.1
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<ul>
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<li><strong>书名</strong>：《SQL必知必会（第5版）》</li>
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<li><strong>作者</strong>： 本·福达</li>
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<li><strong>分类</strong>： 计算机-数据库</li>
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<li><strong>ISBN</strong>：9787115539168</li>
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<li><strong>出版社</strong>：人民邮电出版社</li>
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</ul>
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<h2 id="概述">概述<a role="anchor" aria-hidden="true" tabindex="-1" data-no-popover="true" href="#概述" 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>
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<p>SQL是使用最为广泛的数据库语言，几乎所有重要的DBMS都支持SQL。本书是麻省理工学院、伊利诺伊大学等众多大学的参考教材，由浅入深地讲解了SQL的基本概念和语法，涉及数据的排序、过滤和分组，以及表、视图、联结、子查询、游标、存储过程和触发器等内容，实例丰富，便于查阅。与其他同类图书不同，本书没有过多阐述数据库基础理论，而是专门针对一线软件开发人员，直接从SQLSELECT开始，讲述实际工作环境中最常用和最必需的SQL知识，实用性极强。新版对书中的案例进行了全面的更新，并增加了章后挑战题，便于读者巩固所学知识。</p>
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<h2 id="划线">划线<a role="anchor" aria-hidden="true" tabindex="-1" data-no-popover="true" href="#划线" 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>
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<blockquote>
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<p>SQL是使用最为广泛的数据库语言。</p>
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</blockquote>
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<blockquote>
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<p>数据库（database）保存有组织的数据的容器（通常是一个文件或一组文件）。</p>
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</blockquote>
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<blockquote>
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<p>数据库软件应称为数据库管理系统（DBMS）。数据库是通过DBMS创建和操纵的容器</p>
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</blockquote>
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<blockquote>
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<p>SQL（发音为字母S-Q-L或sequel）是Structured Query Language（结构化查询语言）的缩写</p>
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</blockquote>
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<blockquote>
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<p>Windows用户可以使用Microsoft SQL Server Express。这是强大的SQL Server的一个免费版本，它还包括一个用户友好的客户端叫SQL Server Management Studio。</p>
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</blockquote>
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<blockquote>
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<p>办法就是使用DISTINCT关键字，顾名思义，它指示数据库只返回不同的值。</p>
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</blockquote>
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<blockquote>
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<p>LIMIT 5 OFFSET 5</p>
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</blockquote>
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<blockquote>
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<p>重要的是理解在按多个列排序时，排序的顺序完全按规定进行。</p>
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</blockquote>
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<blockquote>
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<p>如果prod_price列中所有的值都是唯一的，则不会按prod_name排序。</p>
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</blockquote>
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<blockquote>
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<p>提示：按非选择列排序显然，当根据不出现在SELECT清单中的列进行排序时，不能采用这项技术。但是，如果有必要，可以混合使用实际列名和相对列位置。</p>
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</blockquote>
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<blockquote>
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<p>在很多DBMS中，AS关键字是可选的，不过最好使用它，这被视为一条最佳实践。</p>
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</blockquote>
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<blockquote>
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<p>WHERE在数据分组前进行过滤，HAVING在数据分组后进行过滤</p>
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</blockquote>
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<blockquote>
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<p>使用HAVING时应该结合GROUP BY子句，而WHERE子句用于标准的行级过滤。</p>
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</blockquote>
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<blockquote>
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<p>在SELECT语句中，子查询总是从内向外处理。</p>
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</blockquote>
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<blockquote>
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<p>关系表的设计就是要把信息分解成多个表，一类数据一个表。各表通过某些共同的值互相关联（所以才叫关系数据库）。</p>
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</blockquote>
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<blockquote>
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<p>将数据分解为多个表能更有效地存储，更方便地处理，并且可伸缩性更好。但这些好处是有代价的。</p>
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</blockquote>
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<blockquote>
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<p>由没有联结条件的表关系返回的结果为笛卡儿积。检索出的行的数目将是第一个表中的行数乘以第二个表中的行数。</p>
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</blockquote>
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<blockquote>
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<p>目前为止使用的联结称为等值联结（equijoin），它基于两个表之间的相等测试。这种联结也称为内联结（inner join）</p>
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</blockquote>
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<blockquote>
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<p>不要联结不必要的表。联结的表越多，性能下降越厉害。</p>
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</blockquote>
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<blockquote>
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<p>自联结（self-join）、自然联结（natural join）和外联结（outer join）。</p>
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</blockquote>
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<blockquote>
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<p>联结包含了那些在相关表中没有关联行的行。这种联结称为外联结。</p>
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</blockquote>
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<blockquote>
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<p>UNION几乎总是完成与多个WHERE条件相同的工作。UNION ALL为UNION的一种形式，它完成WHERE子句完成不了的工作。如果确实需要每个条件的匹配行全部出现（包括重复行），就必须使用UNION ALL，而不是WHERE。</p>
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</blockquote>
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<blockquote>
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<p>视图是虚拟的表。与包含数据的表不一样，视图只包含使用时动态检索数据的查询。</p>
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</blockquote>
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<blockquote>
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<p>事务处理是一种机制，用来管理必须成批执行的SQL操作，保证数据库不包含不完整的操作结果。</p>
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</blockquote>
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<blockquote>
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<p>管理事务的关键在于将SQL语句组分解为逻辑块，并明确规定数据何时应该回退，何时不应该回退。</p>
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</blockquote>
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<blockquote>
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<p>一般的SQL语句都是针对数据库表直接执行和编写的。这就是所谓的隐式提交（implicit commit），即提交（写或保存）操作是自动进行的。</p>
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</blockquote>
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<h2 id="笔记">笔记<a role="anchor" aria-hidden="true" tabindex="-1" data-no-popover="true" href="#笔记" 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>
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<h2 id="书评">书评<a role="anchor" aria-hidden="true" tabindex="-1" data-no-popover="true" href="#书评" 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>
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<h2 id="点评">点评<a role="anchor" aria-hidden="true" tabindex="-1" data-no-popover="true" href="#点评" 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></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
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