Help needed with SQL

Goodday

I've got a question on SQL. About the following query. This query give the desired result but because i needed to group by [klacht].[actie] the results show more lines in the table then wanted. I would want to join the ones with the same [boekingnr](like the ones marked in red below) into one. Anyone know how to do this?



SELECT [Boeking].[landkort], [klacht].[boekingnr], Count([Klacht].[klachtnr]) AS [aantal klachten], IIf([Klacht].[actie]=On,COUNT(klacht.actie),'-') AS [actie ondernomen]
FROM Boeking INNER JOIN Klacht ON [Boeking].[boekingnr]=[Klacht].[boekingnr]
WHERE [Boeking].[boekingnr]=[Klacht].[boekingnr]
GROUP BY [Boeking].[landkort], [klacht].[boekingnr], [klacht].[actie];


landkort -boekingnr- aantal klachten- actie ondernomen
DE 5 1 1
DE 5 1 -
DE 10 1 -
ES 2 1 1
ES 7 1 -
ES 9 1 1
I 4 1 1
NL 1 1 1


Thanx..

Can I just ask what RDBMS you're using? Also I'm not used to seeing all those '[' and ']' what are they for?

christo