Why don't you write in words what you are trying to accomplish.
To me, it looks like the query should be:
select * from R where a2 > a1;
D'laila Pereira wrote:
>
> i have the following table R
> id a1 a2
> 1 A B
> 2 A B
> 3 B C
> 4 C A
> 5 B C
>
> and to write q uery thats outputs the following
> id a1 a2
> 1 A B
> 2 A B
> 3 B C
> 5 B C
>
> Is the following query correct?
> select *
> from (select *
> from R
> groupby a1) as T1,
> (select *
> from R
> groupby a1) as T2,
> where T1.id<>T2.id
> AND T1.a1=T2.a1
> AND T1.a2=T2.a2;
>
> please correct.
>
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