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19 lines
1.8 KiB
HTML
19 lines
1.8 KiB
HTML
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<h1>SQL AVG() 函数</h1>
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<h2>AVG() 函数</h2> <p>AVG() 函数返回数值列的平均值。</p> <h3>SQL AVG() 语法</h3> <div class="code notranslate"><pre><code class="language-sql"><div> SELECT AVG(column_name) FROM table_name</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 "Products" 表的数据：</p> <table class="reference notranslate">
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<tr>
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<th>ProductID</th> <th>ProductName</th> <th>SupplierID</th> <th>CategoryID</th> <th>Unit</th> <th>Price</th> </tr>
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<tr>
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<td>1</td> <td>Chais</td> <td>1</td> <td>1</td> <td>10 boxes x 20 bags</td> <td>18</td> </tr>
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<tr>
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<td>2</td> <td>Chang</td> <td>1</td> <td>1</td> <td>24 - 12 oz bottles</td> <td>19</td> </tr>
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<tr>
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<td>3</td> <td>Aniseed Syrup</td> <td>1</td> <td>2</td> <td>12 - 550 ml bottles</td> <td>10</td> </tr>
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<tr>
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<td>4</td> <td>Chef Anton's Cajun Seasoning</td> <td>2</td> <td>2</td> <td>48 - 6 oz jars</td> <td>21.35</td> </tr>
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<tr>
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<td>5</td> <td>Chef Anton's Gumbo Mix</td> <td>2</td> <td>2</td> <td>36 boxes</td> <td>25</td> </tr>
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</table>
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<h2>SQL AVG() 实例</h2> <p>下面的 SQL 语句从 "Products" 表的 "Price" 列获取平均值：</p> <div class="example margin-b-10"> <h2 class="example">实例</h2> <pre><code class="language-sql"><div class="example_code notranslate"> SELECT AVG(Price) AS PriceAverage FROM Products; </div></code></pre> </div> <p>下面的 SQL 语句选择价格高于平均价格的 "ProductName" 和 "Price" 记录：</p> <div class="example margin-b-10"> <h2 class="example">实例</h2> <pre><code class="language-sql"><div class="example_code notranslate"> SELECT ProductName, Price FROM Products<br/>WHERE Price>(SELECT AVG(Price) FROM Products); </div></code></pre> </div> <br/><div class="text-center padding-10 margin-t-5">
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