Hi,
According to the following report, I think using "except" would be the best
way to do. Thank you!
Jack
EXPLAIN
SELECT DISTINCT a.c1
FROM test_j2 a
WHERE a.c1 NOT IN (SELECT DISTINCT b.c1 FROM test_j1 b);
Unique (cost=54544.91..54547.41 rows=50 width=6)
-> Sort
>
> Try to get some records not in another table. As the following, please
> advise which one will be the best way to do. Or is there any other way
to do
> better?
>
> SELECT DISTINCT a.c1
> FROM test_j2 a
> WHERE a.c1 NOT IN (SELECT DISTINCT b.c1 FROM test_j1 b);
>
> SELECT a.c1 FROM test_j2 a
>
