MySQL-请问这条sql语句如何，给分析下

Question

SELECT a.* FROM trade AS a WHERE a.code  IN ( SELECT b.code FROM trade AS b GROUP BY b.code HAVING COUNT(b.code)>1) 

Answer 1

应该是执行了 1w X 1w 导致的

因为 mysql 的 in 子查询会被转为 exists

@mysql中的in问题