Researchers continue to find ways by which SQL is better taught. While the language itself is easy, students find it challenging to grasp. This is aggravated with queries that require second-order logic conditions. SQL does not have a construct for universal quantification, which must be done through the negation of SQL's EXISTS construct. This paper describes a tool, RX, that tutors SQL programmers how to formulate SQL queries that require second-order logic conditions. The paper also reports on an experiment that evaluates RX.