The ability to use SQL-LDAP to query between 2 different data sources and/or 2 different containers to do a relational query would be extremely helpful. Being able to query members of a group & do a join or something that would allow you to look at those members for a specific attribute value or if it exists.
For example : SELECT $member from "cn=GroupA,ou=groups,o=directory" WHERE $employeeID IS NULL
See topic sql-ldap-t26247.html