Hi there,
Thanx for your speedy answer.
Good question. I am including another screenshot. This timeit is of the database definition. Most of them are 50 character VARCHAR, except for the dates, which are DATETIME (date_added) and DATE (datum) and of course the primary ID,which is an 11 character INT.
At first I had defined that NULL should be allowed ("NULL toestaan"

, which meant all the 0's (zeros) were replaced with NULL. So then I changed that to NULL allowed: NO.
Perhaps I should change the data type of the numerical fields to another data type? Can you confirm? If so, which type? INT? DECIMAL? ...?
Thanx,
Thom