A cross join that does not have a WHERE clause produces the Cartesian product of the tables involved in the join. The size of a Cartesian product result set is the number of rows in the first table multiplied by the number of rows in the second table. The following example shows a Transact-SQL cross join.
However, if a WHERE clause is added, the cross join behaves as an inner join. For example, the following Transact-SQL queries produce the same result set.