1. A method of processing a database service query, comprising: receiving a service query, obtaining a sum of terms associated with the service query by expanding at least one nested term into one or more un-nested terms, evaluating the sum of terms as 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.
1. A method of processing a database service query, comprising: receiving a service query, obtaining a sum of terms associated with the service query by expanding at least one nested term into one or more un-nested terms, evaluating the sum of terms as 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. 8. The method of claim 1 , wherein: if the service query comprises a term having at least two NOT operators, deleting or disregarding from the sum of terms a third-order term corresponding to the term having at least two NOT operators.