The power of a relational database system is evident when you combine results from one table with those from another. Microsoft Jet is flexible in the type and format of the SQL statements used to create a relational join between tables. In addition to joins in which the linking criteria is specified in the WHERE clause, Microsoft Jet SQL can use the JOIN clause to specify inner joins, left and right outer joins, and self-joins, as well as non-equi-joins, in which the linking criterion isn’t a match in values between two tables, but a generic conditional expression that evaluates to True. Microsoft Jet also supports the UNION statement, which concatenates the results of two or more SELECT statements.