第1个回答 2020-06-18
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';