Hi guys, let's say I have 2 tables.

First table has only one field (UNIQUE KEY) : TOWN

Second table has 2 fields : TOWN and MALEFEMALE

MALEFEMALE can have 3 values : F (female), M (male), U (unknown)

I want to join both tables and as a result, get 4 fields :

TOWN
NUMBERFEMALES
NUMBERMALES
NUMBERUNKNOWN

How can I do that ?

How to do that will depend on your DBMS and version. Newer DBMS versions have a CASE statement that you can use like this:

SELECT town,
SUM( CASE WHEN malefemale='F' THEN 1 ELSE 0 END) numberfemales,
SUM( CASE WHEN malefemale='M' THEN 1 ELSE 0 END) numbermales,
SUM( CASE WHEN malefemale='U' THEN 1 ELSE 0 END) numberunknown
FROM table
GROUP BY town;

Older versions of Oracle can achieve same result using the DECODE function.

Thanks, worked!