详解MySQL分组排序求Top N
MySQL分组排序求Top N 表结构 按照grp分组，按照num排序，每组取Top 3，输出结果如下： 源代码： SELECT FROM score AS t3 WHERE ( SELECT COUNT() FROM score AS t1 LEFT JOIN score AS t2 ON t1.grp = t2.grp AND t1.n
<p>MySQL分组排序求Top N</p>表结构
按照grp分组，按照num排序，每组取Top 3，输出结果如下：
源代码：
SELECT FROM score AS t3
WHERE (
SELECT COUNT() FROM score AS t1
LEFT JOIN score AS t2
ON t1.grp = t2.grp AND t1.num < t2.num
WHERE t1.id = t3.id
) < 3
ORDER BY t3.grp ASC, num DESC
在where中可以通过子查询创造一个新的变量来过滤。
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