A cartesian join is a join of every row of one table to every row of another table. This normally happens when no matching join columns are specified. For example, if table A with 100 rows is joined with table B with 1000 rows, a cartesian join will return 100,000 rows. Something to be avoided!
Note: A query must have at least (N-1) join conditions to prevent a cartesian product, where N is the number of tables in the query.
Using Oracle join syntax:
SELECT * FROM emp, dept;
SELECT * FROM emp, dept WHERE dept.deptno = 10 AND emp.sal > 10000;
Using ANSI join syntax:
SELECT * FROM emp CROSS JOIN dept;
 Also see
|Glossary of Terms|