mysql查询（按...排序）很慢

Question

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

Answer 1

您的查询格式不正确。请尝试以下查询：

178

您可能还需要在 select clientid, ROW_NUMBER() OVER ( partition by clientid ORDER BY max(calendar) desc ) from STATS group by clientid 上建立索引，并且可能（您可能不需要）在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 上