Eliminating reversed duplicate rows 1

[raynalb]

My SQL is a little rusty. Suppose I have Table1 with fields X and Y:
X Y
-- --
A B
A C
B A

How would I write the SQL to eliminate the 3rd row because it is a duplicate of the 1st row when reversed?

Thanks,
Ray

 

[markros]

select * from Table1 T1
where not exists (select * from Table1 T2 where T1.X = T2.Y and T1.Y = T2.X)

Alternative solution

select X, Y from Table1 T1
EXCEPT
select Y, X from Table1 T1

PluralSight Learning Library

 

[raynalb]

Thanks markros. Worked great.

Regards,
Ray