MySQL: Subqueries with multiple results

Question

I can't find the error in my (my)sql query:

SELECT * 
FROM   KUNDEN 
WHERE  KUNR IN (SELECT DISTINCT KUNR 
                FROM   AUSLEIHE) 

kunr: integer

Everytime it says, that there are multiple results in the subquery . But my target is to check, if the subquery contains the value of kunr. It would be very nice, if you could help me.

Answer 1

What about JOIN

SELECT * FROM   KUNDEN  k 
JOIN AUSLEIHE a ON (k.KUNR  = a.KUNR ) 

Answer 2

(SELECT KUNR 
FROM   AUSLEIHE GROUP BY KUNR)

Try this subquery.

Answer 3

just for laughs

SELECT * FROM   KUNDEN  k 
LEFT JOIN AUSLEIHE a ON (k.KUNR  = a.KUNR )
where   a.KUNR is not null