有这样的sql
select * from
(select * FROM
(select * from
(select * from
(select * from tb)a)a)a) a像这样的语句把里面的语句转成临时表快些还是有什么别的优化办法?
select * from
(select * FROM
(select * from
(select * from
(select * from tb)a)a)a) a像这样的语句把里面的语句转成临时表快些还是有什么别的优化办法?
要是递归的话,需要公用表表达式的写法, with t as ( select x,xx,xxx from a where 1=1 union select x,xx,xxx from t inner join a on x=xx)
不知道可行不,有没有具体的方案?求各位大神支招