I am trying to limit results pulled from two tables, each with all states and congressional districts, to specified congressional districts. I want each college to appear once matched to each congressional district (that is in one table and is easy to do) and also include a column from a second table with the Representative. My syntax, below, produces far too many results, matching college and district and Representative many times.

The syntax:

select a.college, a.state, a.cd, b.rep from a, b

where

a.state = "al" and a.cd = "3" or a.state = "az" and a.cd = "1" and

a.state = b.state and a.cd = b.cd

What do I do to limit to single match for each college in the specified congressional districts?