The JOIN operations are among the possible tableExpressions in a FROM clause. (You can also perform a join between two tables using an explicit equality test in a WHERE clause, such as WHERE t1.col1 = t2.col2.)

The JOIN operations are:

• Specifies a join between two tables with an explicit join clause.

• Specifies a join between two tables with an explicit join clause, preserving unmatched rows from the first table.

• Specifies a join between two tables with an explicit join clause, preserving unmatched rows from the second table.

• Specifies a join that produces the Cartesian product of two tables. It has no explicit join clause.

• Specifies an inner or outer join between two tables. It has no explicit join clause. Instead, one is created implicitly using the common columns from the two tables.

In all cases, you can specify additional restrictions on one or both of the tables being joined in outer join clauses or in the WHERE clause.

For information on which types of joins are optimized, see .