SQL on and 和 on where 的区别

2.where是全部连接完后，对临时表进行筛选，筛选对左表和右表都有效

在使用inner join时，on   and与on  where条件的区别：不管是对左表还是右表进行筛选，on  and和on  where都会对生成的临时表进行过滤。

1. 新建表 t1

2. 新建表 t2

3. 关联查询：

select * from t1 left join t2 on t1.user_id = t2.user_id

on and 

a.) 对左表加and 条件

select * from t1 left join t2 on t1.user_id = t2.user_id and t1.deleted = 0

b.) 对右表加and 条件

select * from t1 left join t2 on t1.user_id = t2.user_id and t2.deleted = 0

 on where

select * from t1 left join t2 on t1.user_id = t2.user_id where t1.deleted = 0

select * from t1 left join t2 on t1.user_id = t2.user_id where t2.deleted = 0

SQL on and 和 on where 的区别

标签：str   ted   临时   code   col   sele   记录   select   har