Detecting Logical Errors in SQL Queries
نویسندگان
چکیده
Queries that are contradictory, i.e. always return the empty set, are quite often written in exams of database courses. Although such queries are obviously not intended, they are executed in current database management systems (e.g., Oracle) without any warning. Of course, questions like the satisfiability are in general undecidable, but we give a quite simple algorithm that can handle a surprisingly large subset of SQL queries. We then analyze unnecessary logical complications. Furthermore, we discuss possible runtime errors in SQL queries and show how a test for such errors can be reduced to a consistency check. We believe that future database management systems will perform such checks and that the generated warnings will help to develop code with fewer bugs in less time.
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