Question

I have 2 tables in which about 80% of primary keys is the same. How can I SELECT:

• all rows from table A where there is no primary key in other table (e.g. row have the primary as 432, but there is no 432 in table B – so we want to select it)

• all rows from either table when there is primary key of e.g. 784 in both of them.

Answer 1

select common records:

Select * from TableA a
inner join TableB b on a.id = b.id

select unique tableA records:

Select * from tableA
where id not in (select id from TableB)