12. A method of processing a directory service query, comprising: receiving a directory service query, obtaining a sum of terms by expanding at least one nested term into one or more un-nested terms, mapping the sum of terms to a plurality of SQL instructions, wherein the sum of terms comprises one or more positive terms and one or more negative terms, determining a plurality of results associated with the sum of terms by executing, using a processor, the SQL instructions, collecting, into a first list, any of the results associated with the one or more negative terms, collecting, into a second list, any of the results associated with the one or more positive terms while omitting from the second list any of the results that are in the first list, and providing one or more of the results from the second list to a user.
13. The method as claimed in claim 12 , further comprising expanding each term to remove NOT operators.