https://zxdd.com/index.php?action=history&feed=atom&title=%E6%A8%A1%E6%9D%BF%3ASQL%E5%88%86%E7%BB%84%E6%9F%A5%E8%AF%A2 2026-06-09T23:09:02Z 本wiki上该页面的版本历史 MediaWiki 1.38.4 https://zxdd.com/index.php?title=%E6%A8%A1%E6%9D%BF:SQL%E5%88%86%E7%BB%84%E6%9F%A5%E8%AF%A2&diff=506&oldid=prev 2021-04-05T08:56:52Z

<p>创建页面，内容为“&#039;&#039;&#039;GROUP BY&#039;&#039;&#039;子句可以对一列或多列进行分组，与聚合函数一起使用可以实现分组统计。 {| class=&quot;wikitable&quot; style=&quot;width: 100%; ! 聚合…”</p> <p><b>新页面</b></p><div>&#039;&#039;&#039;GROUP BY&#039;&#039;&#039;子句可以对一列或多列进行分组，与聚合函数一起使用可以实现分组统计。<br /> <br /> {| class=&quot;wikitable&quot; style=&quot;width: 100%;<br /> ! 聚合函数<br /> ! 描述<br /> ! 示例<br /> |-<br /> |&#039;&#039;&#039;COUNT(&#039;&#039;&#039;列名 或 &#039;&#039;&#039;*)&#039;&#039;&#039;<br /> |行数。&lt;code&gt;COUNT(列名)&lt;/code&gt;统计该列行数，存在空值不计数。&lt;code&gt;COUNT(*)&lt;/code&gt;统计行数，一行中存在空值也计数。<br /> | &#039;&#039;&#039;SELECT&#039;&#039;&#039; 列名, &#039;&#039;&#039;COUNT(&#039;&#039;&#039;列名2&#039;&#039;&#039;)&#039;&#039;&#039; &#039;&#039;&#039;FROM&#039;&#039;&#039; 表名 &#039;&#039;&#039;GROUP BY &#039;&#039;&#039; 列名;<br /> |-<br /> |&#039;&#039;&#039;MIN(&#039;&#039;&#039;列名&#039;&#039;&#039;)&#039;&#039;&#039;<br /> |最小值。值为字符串时，按字符序列进行比较。<br /> | &#039;&#039;&#039;SELECT&#039;&#039;&#039; 列名, &#039;&#039;&#039;MIN(&#039;&#039;&#039;列名2&#039;&#039;&#039;) AS&#039;&#039;&#039; 列2最小值 &#039;&#039;&#039;FROM&#039;&#039;&#039; 表名 &#039;&#039;&#039;GROUP BY &#039;&#039;&#039; 列名;<br /> |-<br /> |&#039;&#039;&#039;MAX(&#039;&#039;&#039;列名&#039;&#039;&#039;)&#039;&#039;&#039;<br /> |最大值。值为字符串时，按字符序列进行比较。<br /> | &#039;&#039;&#039;SELECT&#039;&#039;&#039; 列名, &#039;&#039;&#039;MAX(&#039;&#039;&#039;列名2&#039;&#039;&#039;) &#039;&#039;&#039; &#039;&#039;&#039;FROM&#039;&#039;&#039; 表名 &#039;&#039;&#039;GROUP BY &#039;&#039;&#039; 列名 &#039;&#039;&#039;ORDER BY&#039;&#039;&#039; 列名;<br /> |-<br /> |&#039;&#039;&#039;SUM(&#039;&#039;&#039;列名&#039;&#039;&#039;)&#039;&#039;&#039;<br /> |所有值的和。<br /> | &#039;&#039;&#039;SELECT&#039;&#039;&#039; 列名, &#039;&#039;&#039;SUM(&#039;&#039;&#039;列名2&#039;&#039;&#039;) &#039;&#039;&#039;, &#039;&#039;&#039;MAX(&#039;&#039;&#039;列名2&#039;&#039;&#039;) &#039;&#039;&#039; &#039;&#039;&#039;FROM&#039;&#039;&#039; 表名 &#039;&#039;&#039;GROUP BY &#039;&#039;&#039; 列名;<br /> |-<br /> |&#039;&#039;&#039;AVG(&#039;&#039;&#039;列名&#039;&#039;&#039;)&#039;&#039;&#039;<br /> |算术平均值。<br /> | &#039;&#039;&#039;SELECT&#039;&#039;&#039; 列名, &#039;&#039;&#039;AVG(&#039;&#039;&#039;列名2&#039;&#039;&#039;) &#039;&#039;&#039;, &#039;&#039;&#039;SUM(&#039;&#039;&#039;列名2&#039;&#039;&#039;) &#039;&#039;&#039; &#039;&#039;&#039;FROM&#039;&#039;&#039; 表名 &#039;&#039;&#039;GROUP BY &#039;&#039;&#039; 列名;<br /> |-<br /> |}</div>

Eric