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

Dave Smith <dave(dot)smith(at)candata(dot)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