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mysql中group by与having合用注意事项分享_MySQL

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Release: 2016-06-01 13:25:34
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group by函数应该的使用应该是SELECT 列表中指定的每一列也必须出现在 GROUP BY 子句中,除非这列是用于聚合函数,但是今天帮同事调试一个mysql中的group by函数,让我大跌眼镜,当时感觉不可思议,然后回来做了个简化版试验,试验过程如下:

mysql表结构


mysql> desc t;
+――-+――――

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