Question

I have following tables;

 A   B                       A   B
 _____                       _____
 1   t                       7   a
 2   r                       5   d
 3   e                       3   e
 4   f
 5   d
 6   s
 7   a

And, output should be ;

 A   B                     
 _____                     
 1   t                      
 2   r                     

 4   f

 6   s

In other words I want difference of these two tables . I want region A in this figure.
How can I do that ?

Answer 1

Try this:

SELECT t1.*
FROM t1
LEFT JOIN t2 USING (A, B)
WHERE t2.A IS NULL