select * from mwebrepseloptions where repopt_required not in (10, 20) ....... returns 0
select * from mwebrepseloptions where repopt_required is not null ....returns 139 (correct)
select * from mwebrepseloptions where repopt_required is null ....returns 8 (correct)
select * from mwebrepseloptions where repopt_required <>10 or repopt_required <>20 ....returns 139(wrong)
select * from mwebrepseloptions where repopt_required =10 or repopt_required =20....returns 139(might be correct)
select count(*) from mwebrepseloptions... returns total 147(correct)

Repopt_required Column is defined as number.


My problem is why
select * from mwebrepseloptions where repopt_required <>10 or repopt_required <>20 ....returns 139(wrong)
select * from mwebrepseloptions where repopt_required =10 or repopt_required =20....returns 139(might be correct)


these 2 queries return same number of rows(rather same rows) when <> should return 8 rows and not 139 rows ???


thanks