How do I check if all of a field are equal in a group in SQL

Question

So I have something like

 prop1 | prop2
 aaa   | xxx
 aaa   | xxx
 bbb   | yyy
 bbb   | !yyy
 ccc   | zzz
 ccc   | zzz

now I can group by prop1 and get aaa, bbb, ccc and I can check them individually and find that bbb's two properties dont match,

So how do I do that with sql?

How do I only get 'bbb' as my result?

I may have 2 to many in each group.

Answer 1

I would simply use group by and having:

select prop1
from t
group by prop1
having min(prop2) <> max(prop2);