SQL INNER JOIN

[dedlfix]

Hi!

Ich will alle Spalten von Tabelle B bei der die serial zu Tabelle A identisch ist, aber die number nur in Tabelle B exisitert.
Mein Versuch mit 0 resulst:

SELECT *

FROM B
LEFT JOIN A
ON B.serial=A.serial
WHERE B.serial LIKE '%999%'
AND B.date BETWEEN '2009-11-19 00:00:00' AND '2009-11-19 23:59:59'
AND A.date BETWEEN '2009-11-19 00:00:00' AND '2009-11-19 23:59:59'
AND A.number is NULL
GROUP BY B.number;

  
Was macht das GROUP BY da?  
  
  
Lo!