comparing two tables and removing ones that match

I have two tables. MembID is the only column returned for each. The MembID can be in both tables but I would like to remove the ones that are in both from the results.

I’d like the final return to be 456 and 789 from Table A.

I’ve tried:

select distinct a.membid
from a
 left join b on a.membid = b.membid
and b.num <> 1 

it does not return any results.

Thanks.

Answer

try like below

select distinct a.membid
from a
 left join b on a.membid = b.membid
where b.membid is null