A set of mutation operators for SQL queries that retrieve information from a database is developed and tested against a set of queries drawn from the NIST SQL Conformance Test Suite. The mutation operators cover a wide spectrum of SQL features, including the handling of null values. Additional experiments are performed to explore whether the cost of executing mutants can be reduced using selective mutation or the test suite size can be reduced by using an appropriate ordering of the mutants. The SQL mutation approach can be helpful in assessing the adequacy of database test cases and their development, and as a tool for systematically injecting faults in order to compare different database testing techniques.

We present a tool to automatically generate mutants of SQL database queries. The SQLMutation tool is available on the Web and it can be accessed using two different interfaces: A Web application to interactively generate the mutants and a Web service that allows it to be integrated with other applications developed using different platforms.