On Tue, Feb 7, 2017 at 3:58 PM, Tom Lane <t...@sss.pgh.pa.us> wrote:
> Joel Jacobson <j...@trustly.com> writes:
> > Currently there is no simple way to check if two sets are equal.
>
> Uh ... maybe check whether SELECT set1 EXCEPT SELECT set2
> and SELECT set2 EXCEPT SELECT set1 are both empty?
>
> regards, tom lane
>
>
> Yes, if the wanted result is true or false, something like this:
SELECT EXISTS (TABLE a EXCEPT TABLE b)
OR EXISTS (TABLE b EXCEPT TABLE a) ;
And if a new operator was added (in the same category as UNION and
EXCEPT), it could be:
SELECT EXISTS (TABLE a XORSET TABLE b) ;
What about using the = and <> operators in sets? Is the following
allowed in the standard?
SELECT (TABLE a) <> (TABLE b) ;
