>>Also ... a side note. Have you tried to think of a way
>>to normalize your data?
>What do you mean normalize? I am not very sure, please explain.

You normalize data when data that is identical except in value is kept in a separate table.

In this case, you could have an InstallDate table that would have your Customer Number (use the primary key here) and the number of the month from present (1-48) and the actual date.

This makes it easier to change the number of dates you keep, and to make an update you just scan the table for the Customer Number and update the same field in each record.

HTH
Barbara