Create advanced joins
The topic Create a join shows how to include a WHERE clause in a SELECT statement to join two or more tables on one or more columns. It illustrates natural joins and equi-joins.
This section discusses how to use two more complex kinds of joins, self-joins and outer joins. As described for simple joins, you can define aliases for tables and assign display labels to expressions to shorten your multiple-table queries. You can also issue a SELECT statement with an ORDER BY clause that sorts data into a temporary table.