Base> (Commonly "join", But see also "outer join") A relational dataBase operation which selects rows from two taBles such that the value in one column of the first taBle also appears in a certain column of the second taBle. An example in SQL: select * from A, B where A.x = B.y The column names (x and y in this example) are often, But not necessarily, the same. (1998-11-23)