HCL OneDB extension to outer join syntax
The HCL
OneDB™ extension
to outer-join syntax begins an outer join with the OUTER keyword.
When you use the HCL
OneDB syntax,
you must include the join condition in the WHERE clause. When you
use the HCL
OneDB syntax
for an outer join, the database server supports the following three
basic types of outer joins:
- A simple outer join on two tables
- An outer join for a simple join to a third table
- An outer join of two tables to a third table
An outer join must have a Projection clause, a FROM clause, and a WHERE clause. The join conditions are expressed in a WHERE clause. To transform a simple join into an outer join, insert the keyword OUTER directly before the name of the subordinate tables in the FROM clause. As shown later in this section, you can include the OUTER keyword more than once in your query.
No HCL OneDB extension to outer-join syntax is equivalent to the ANSI right outer join.