Re: Why must SELECT DISTINCT, ORDER BY expressions must appear in target list?

Dave Smith <dave.smith@candata.com> writes:
> ERROR:  For SELECT DISTINCT, ORDER BY expressions must appear in target
> list

> This seems like a bug.

No, it isn't.  Consider

    SELECT DISTINCT x FROM tab ORDER BY y;

Assuming there are multiple values of y for any given x, how would you
expect the result to be sorted?  It's ill-defined.

            regards, tom lane