专家！请问互相包含的SQL问题！

[rolt1]

互相包含的SQL问题

表T1，字段a1,b1
a1 b1
1 5
1 6
1 7
2 4

....

表T2，字段b2
b2
5
6
7



问题
我想知道：表T1里存不存在这样的a1，b1子集，子集中a1相同，b1集合与T2里的b2字段集合（当然是Select b2 from T2）相同。如有，给出这样的a1。

例如：上面的例子中a1=1就是一个。

最好用标准的SQL，不用Cursor，循环....
还可加分

[DeD]

if (select count(*) from t1,t2 where t2.b2=t1.b1)=(select count(*) from t2)
begin
if (select count(*) from (select a1 from t1,t2 where t2.b2=t1.b1 group by t1.a1) test)=1
begin
print '满足条件 '
select distinct a1 from t1,t2 where t2.b2=t1.b1
end
else
print '不满足条件 '
end

[guostong]

select distinct a1 from t1 a where
not exists (select b2 from t2 where b2 not in
(
select b1 from t1 where a1 = a.a1
)
)

[guostong]

select distinct a1 from t1 a where
not exists (select b2 from t2 where b2 not in
(
select b1 from t1 where a1 = a.a1
)
)

[guostong]

或者：
select distinct a1 from t1 a where
not exists
(select b2 from t2 minus select b1 from t1 where a1 = a.a1)

[nononono]

select a1
from (select distinct a1 from t1) as ta
where (select count(*) from t1 where a1=ta.a1)
= (select count(*) from t1,t2 where t1.b1=t2.b2 and t1.a1=ta.a1)

[yangzi]

nononono兄的写法好象可以。

[guostong]

example:
query1 minus query2;

minus is mean:

set in query1 but not in query2

[guostong]

补充：
minus : ORACLE 的操作关键字

[guostong]

更正：
select distinct a1 from t1 a where
not exists
(select b2 from t2 minus select b1 from t1 where a1 = a.a1)
and not exists
(select b1 from t1 where a1 = a.a1 minus select b2 from t2 )

[july]

agree to nononono(？？？？)　

to guostong(笨驴)　:

what is minus