Many thanks!
I have finished what I wanted to do. Your suggestions were very helpful. There were to many different patterns in the Date field (for example : 03-01-2004, 01-03-2004, 03.01.2004, 01.03.2004, 03/01/2004, 01/03/2004, 2004-03-01, 2004-01-03, etc.)
I unfortunately had to go through...