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21 lines
2.7 KiB
HTML
21 lines
2.7 KiB
HTML
<div class="m-bg">
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<h1>SQL SELECT 语句</h1>
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<p class="intro">SELECT 语句用于从数据库中选取数据。</p> <h2>SQL SELECT 语句</h2> <p>SELECT 语句用于从数据库中选取数据。</p> <p>结果被存储在一个结果表中，称为结果集。</p> <h3>SQL SELECT 语法</h3> <div class="code notranslate"><pre><code class="language-sql"><div> SELECT <em>column_name</em>,<em>column_name</em><br/> FROM <em>table_name</em>;</div></code></pre></div> <p>与</p> <div class="code notranslate"><pre><code class="language-sql"><div> SELECT * FROM <em>table_name</em>;</div></code></pre></div> <h2>演示数据库</h2> <p>在本教程中，我们将使用众所周知的 Northwind 样本数据库。</p> <p>下面是选自 "Customers" 表的数据：</p> <table class="reference notranslate">
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<tr>
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<th>CustomerID</th> <th>CustomerName</th> <th>ContactName</th> <th>Address</th> <th>City</th> <th>PostalCode</th> <th>Country</th> </tr>
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<tr>
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<td>1<br/><br/>
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</td> <td>Alfreds Futterkiste</td> <td>Maria Anders</td> <td>Obere Str. 57</td> <td>Berlin</td> <td>12209</td> <td>Germany</td> </tr>
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<tr>
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<td>2</td> <td>Ana Trujillo Emparedados y helados</td> <td>Ana Trujillo</td> <td>Avda. de la Constitución 2222</td> <td>México D.F.</td> <td>05021</td> <td>Mexico</td> </tr>
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<td>3</td> <td>Antonio Moreno Taquería</td> <td>Antonio Moreno</td> <td>Mataderos 2312</td> <td>México D.F.</td> <td>05023</td> <td>Mexico</td> </tr>
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<td>4<br/><br/>
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</td> <td>Around the Horn</td> <td>Thomas Hardy</td> <td>120 Hanover Sq.</td> <td>London</td> <td>WA1 1DP</td> <td>UK</td> </tr>
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<td>5</td> <td>Berglunds snabbköp</td> <td>Christina Berglund</td> <td>Berguvsvägen 8</td> <td>Luleå</td> <td>S-958 22</td> <td>Sweden</td> </tr>
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</table>
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<h2>SELECT Column 实例</h2> <p>下面的 SQL 语句从 "Customers" 表中选取 "CustomerName" 和 "City" 列：</p> <div class="example margin-b-10"> <h2 class="example">实例</h2> <pre><code class="language-sql"><div class="example_code notranslate"> SELECT CustomerName,City FROM Customers; </div></code></pre> </div> <h2>SELECT * 实例</h2> <p>下面的 SQL 语句从 "Customers" 表中选取所有列：</p> <div class="example margin-b-10"> <h2 class="example">实例</h2> <pre><code class="language-sql"><div class="example_code notranslate"> SELECT * FROM Customers; </div></code></pre> </div> <h2>结果集中的导航</h2> <p>大多数数据库软件系统都允许使用编程函数在结果集中进行导航，比如：Move-To-First-Record、Get-Record-Content、Move-To-Next-Record 等等。</p> <p>类似这些编程函数不在本教程讲解之列。如需学习通过函数调用访问数据的知识，请访问我们的 ADO 教程 或者 PHP 教程。</p> <div class="text-center padding-10 margin-t-5">
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