Question

Given two tables :

A with row : [1641, 1468] Amongst others
B with row : [1641, 1468] Amongst others

If I run this :

select distinct A.c1, B.c2
from A, B
where A.c1 <> B.c1 and A.c2 <> B.c2

I was expecting not to get that tuple back. Although when running the command it returns that tuple.

Is there an explanation for this behavior ? Using SQLite.

Answer 1

If you have

A
---
C1 C1
-----
1  2
1  3

.

B
---
C1 C1
-----
1  2
1  3

The join will first produce

A.C1 A.C2 B.C1 B.C2
-------------------
1    2    1    3
1    3    1    2

With distinct and just the selected columns it will be

A.C1 B.C2
---------
1    3
1    2

I suspect you want something like

select distinct A.c1, B.c2
from A, B
WHERE NOT EXISTS (SELECT 1 FROM B WHERE A.C1 = B.C1 AND A.C2 = B.C2)