7种join连接查询

内链接--取共有部分

select <select_list>

from tableA a

inner join tableB b

on a.key =b.key

 

 

 ab共有加a的独有（全a）--左链接

select<select_list>

from tableA a

left join tableB b

on a.key=b.key 

 

b独有+ab共有(全b)

 

select<select_list>

from tableA a

right join tableB b

on a.key=b.key

 

select<select_list>

frin tableA a

left join tableB b

on a.key =b.key

where b.key is null

 

select<select_list>

from tableA a

right join tableB b

on a.key=b.key

where a.key is null

 

 

 

select<select_list>

from tableA a

full outer join tableB b

on a.key=b.key

 

 

select<select_list>

from tableA a

full outer join tableB b

on a.key=b.key

where a.key is null

or b.key is null