We need to fill in the (mobile) carrier in a customer table with field MobileNr.
Carrier is defined (here) by the first 4 left characters of the mobile #.
We have a table NumberCarrier fields Left4 (with left 4 positons) and Carrier.
Q1: I can't define a relationship between Left(MobileNr,4) and Left4 (as far as I know). Correct?
Q2: Of course we can search the NumberCarrier table for every record (or make a help-table with first4 positions of customer phone #)
but is there no better way?