Compare 2 columns in two tables

[maxwcc]

How do you compare 2 ID columns of int type of one table with that of another.
If the combo columns of the record x of table1 matches that with any record with the same combo columns in table2, do not select the record x.

[YuckFou]

if you want select values from table1 that don't exist in table2 you can use "NOT EXISTS" or LEFT/RIGHT/FULL [OUTER] JOIN...

select * from table1 x where not exists (select * from table2 where a=x.a)

select * from table1 x left outer join table2 y on y.a=x.a
where y.a is null

select * from table1 x right outer join table2 y on y.a=x.a
where x.a is null

select * from table1 x full outer join table2 y on y.a=x.a
where x.a is null or y.a is null