> I have two tables, postal_code, and postal_zone, since I am in
> Canada a postal code looks like this: X1X 1X1
>
> The postal_zone contains a key, that is part of a postal code, it
> might be X1X 1X1, X1X 1X, X1X 1, X1X, X1 or X
>
> say I have the following zones:
> 1 X1X 1X1
> 2 X1X 1X
> 3 X1X 1
> 4 X1X
> 5 X1
> 6 X
>
> I have the following postal codes
>
> X1X 1X1 must match 1 but not 2,3,4,5 or 6
> X1X 2E4 must match 4 but not 1,2,3,5 or 6
> X3F 2Z7 must match 6 but not 1,2,3,4 or 5
>
> I am at a loss on how to do this,

Actually, what exactly are you trying to do?