Thanks for your reply, Dave!
That gives me the following result - correct number of rows, but not the correct content...
CustNo ContractNo RNo DateFrom Discount
2 3 2 2010-01-01 00:00:00.000 NULL
1 1 3 2010-01-01 00:00:00.000 NULL
1 1 2 2010-01-01 00:00:00.000 NULL
1 1 1 2010-01-01 00:00:00.000 NULL
1 1 1 2008-01-01 00:00:00.000 50
1 1 2 2009-01-01 00:00:00.000 50
I think I must try...