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sql join中on条件后接and和where


目录

​​场景1:left join + on a.xx = b.xx and a.xx2 = 'aa'​​

​​场景2:left join + on a.xx = b.xx and b.xx2 = 'aa'​​

​​场景3:left join + on a.xx = b.xx where b.xx2 = 'aa'​​

​​场景4:inner join + on a.xx = b.xx where a.xx2 = 'aa'​​

​​场景5:inner join + on a.xx = b.xx and  a.xx2 = 'aa'​​

​​场景6:inner join + on a.xx = b.xx  and  b.xx2 = 'aa'​​

​​总结​​

场景1:left join + on a.xx = b.xx and a.xx2 = 'aa'

sql join中on条件后接and和where_数据

场景2:left join + on a.xx = b.xx and b.xx2 = 'aa'

sql join中on条件后接and和where_sql_02

场景3:left join + on a.xx = b.xx where b.xx2 = 'aa'

sql join中on条件后接and和where_数据_03

场景4:inner join + on a.xx = b.xx where a.xx2 = 'aa'

sql join中on条件后接and和where_sql_04

场景5:inner join + on a.xx = b.xx and  a.xx2 = 'aa'

sql join中on条件后接and和where_sql_05

场景6:inner join + on a.xx = b.xx  and  b.xx2 = 'aa'

sql join中on条件后接and和where_sql_06

总结

1、where 条件可以理解为,关联后,数据作为一个整体的过滤条件

2、on 后面的and 条件为关联条件,如果是left join,则不对主表记录行数产生影响;如果是inner join则,效果等同于where条件

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