Need help with Where Clause

[Guest]

I am going to try and explain this as best possible. My database is for
Accounts Receivables. We assign new customers a company number, we have 7
Branches, each Branch has a number range between 00001 thru 9999. At the
moment they are assigned randomly. I need to track numbers used, and numbers
not used. The query I have now does track what is used, but does not include
the full range. I have been trying this with the WHERE clause, but I have not
been able to get the syntax right or I am just looking at it wrong. I will
include my qry. I left off the WHERE because it just was not correct.
Thanks

SELECT ARDetailAging.[co-number] AS Branch,
ARDetailAging.[cust-number] AS CustomerNumber,
ARDetailAging.[divn-number] AS SubBranch,
ARDetailAging.[ref-number],
ARDetailAging.[cust-name] AS CustomerName

FROM ARDetailAging LEFT JOIN NAMEADDR ON (ARDetailAging.[cust-name] =
NAMEADDR.[cust-name]) AND (ARDetailAging.[co-number] = NAMEADDR.[co-number])


ORDER BY ARDetailAging.[co-number], ARDetailAging.[cust-number],
ARDetailAging.[cust-name], ARDetailAging.[cust-number];

 

[Guest]

I think what I'm looking for is an IIF Statement. How can I track what is
used between the 0001 thru 9999 range per BRANCH?