数据库 用一条sql语句得到两个表中数据的统计

用一条sql语句得出A和B的剩余数量

select a.name,a.buy-b.sell as left
from
(
select name,sum(buy) as buy
from tableA
where name in ('A','B')
group by name
) a
left outer join
(
select name,sum(sell) as sell

from tableB

where name in ('A','B')
group by name
) b
on a.name = b.name

create procedure sp_deletealldata as exec sp_msforeachtable 'alter table ? nocheck constraint all' exec sp_msforeachtable 'alter table ? disable trigger all' exec sp_msforeachtable 'delete from ?' exec sp_msforeachtable 'alter table ? check constraint all' exec sp_msforeachtable 'alter table ? enable trigger all' exec sp_msforeachtable 'select * from ?' gosp_deletealldata这个脚本创建了一个命名为sp_deletealldata的存储过程，前面两行语句分别禁用约束和触发器，第三条语句才是真正地删除所有数据，接下里的语句分别还原约束和触发器，最后一条语句是显示每个表中的记录，当然这条语句也可以不要，我只是想确认一下是否清空了所有表而已。