HI ScottASD,
Thank you for your purchase.

Each Zip code must have unique ID which will be used to represent the different zip code

for example if you have table 1 with 2 columns

column 1    column 2(zipcodes)

1                    12345

2                    54321

3                    45678

and make other table 2 with this columns

column 1    column 2

test1                1

test2                2

test 3               3

then for column 2 in the second table change it to string and make a relation , to get the ID value ( from table 1) from column 1 and display the values from column 2.

the result will be this

column 1       column 2

test1                12345

test2                 54321

test3                 45678

So for each zipcode that you have in the table you must have his unique ID that will be replaced for the second table.

Best regards.