Mysql查询（order by）很慢

Posted 2023-01-12

当我从另一个表中使用ORDER BY时，它的工作速度非常慢。如何进行查询

SELECT u.*, (SELECT COUNT(id) FROM operations o WHERE o.userId=u.userId and o.status=1) as countOperations FROM users u ORDER BY countOperations

答案

您的查询格式不正确。尝试以下查询：

select col1, col2, ..., coln, count(id) countOperations, SUM(o.sumRUB) sumRUB
from users u
inner join operations o 
  on o.userId=u.userId and o.status=1
group by col1, col2, ..., coln
ORDER BY countOperations

你可能还需要operations(userId, status)上的索引以及可能（你可能不需要）users(col1, col2, ..., coln)