Inner Join Without Duplicates, Is It Possible?

Given these two tables Table A1 has two rows with the same value 'a' A1 a a Table A2 has two rows with primary key value A,B and they are associated with 'a' A2 PK col2 A a B

Solution 1:

You can wipe out the duplicates by using DISTINCT

selectdistinct
  A1.col1,
  A2.PK
from
  A1
  innerjoin A2
          on A1.col1 = A2.col2

Solution 2:

If distinct is not restricted

SELECTDISTINCT a.*, b.pk
FROM    A1 a
INNERJOIN A2 b ON (a.[test] = b.fk)

Solution 3:

There are no joining condition in the post, so we need to go for cross join. I have applied cross join and restrict the duplicate values using distinct.

Selectdistinct A1.Col1, A2.Pk
From A1 ,A2 

Solution 4:

"and restrict the duplicate values using distinct." at least in Postgres 9+ DISTINCT eliminates existing duplicates but not preventing or restricting its appearing.

Solution 5:

SELECTDISTINCT A.* 
FROM aTable AS A 
     INNER JOIN 
     bTable AS B USING(columnId)