Quote Originally Posted by stampede View Post
Try to search for some info on "Database normalization".
Very good hint into the right direction. Thanks.

You then use a JOIN during your SELECT queries to merge the two tables:
SELECT * from Invoices,Invoice_Line where Invoices.id = Invoice_Line.invoice_id;
Jup, as far as I read by know, this is exactly what database normalization is about. I will solve it that way.

Thanks for the good answers!