A teaching system for SQL

Skill in writing SQL queries is a fundamental outcome expected by industry from any university course in Database Systems. Students often have difficulty with fundamental SQL concepts such as multitable joins, aggregation and grouping. This paper describes teaching software, which supports students learning these concepts. The system, called esql, is similar to a normal query interface, except that the response to a SELECT statement is not merely to show the result, but instead to show a sequence of images, giving a step-by-step account of how the query result is determined.