SQL数据库中两个表A,B存放内容不一样，需要关联两表查询数据.

问题1:E机构里面的每个名称下面有多少个价格，如果要制定某一个名称，可以在where条件中增加name最为条件:

select

a.name

,

count(price)

from

a,b

where

a.mediid

=

b.mediid

and

a.forgid

=

b.forgid

and

a.forgid

=

'E'

group

by

a.name

如果要去掉重复价格可以增加distinct，如下:

select

a.name

,

count(distinct

price)

from

a,b

where

a.mediid

=

b.mediid

and

a.forgid

=

b.forgid

and

a.forgid

=

'E'

group

by

a.name

问题2:查询E机构下面，两个表中编号相同的项目

select

count(name)

from

a,b

where

a.mediid

=

b.mediid

and

a.forgid

=

b.forgid

and

a.forgid

=

'E'

select a.d,b.b1 from A a left join B b on a.A1=b.B1 where a.C = ?（默认提供左连接写法，根据你的需求自己选择适合的连接）

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