How does SQL get the value of the variable from the form in access?

In the example I am working on, I am polling the data for specific info for each person in an office. Currently, since the query is in the access file, I check he current form that calls up the query. In that form is a text field that holds the current office code. Let's say that it is in [Forms]![aform]![loc]. How do I code my SQL statement on the SQL server to see this value?

Or are you saying YES to my statement about making a table that holds the current office location code? If this is what you are suggesting, what happens when multiple offices try and access this query at the same time?