ODBC outer join syntax

In ODBC, you can use outer join syntax in a vendor escape clause to make outer joins portable in your SQL statements.

The following extended SQL syntax specifies an outer join.

table-name: Specifies the name of the table that you want to join.
LEFT: Performs a left outer join.
RIGHT: Performs a right outer join.
FULL: Performs a full outer join.
table-name: Specifies the name of the table that you want to join with the previous table.
outer-join: Specifies the result of an outer join that you want to join with the previous table. (Use the syntax above without the leading keyword oj.)
search-condition: Specifies the condition on which rows are joined.

Example: You can use either of the following forms of the escape clause to perform an outer join. In this example, a vendor escape clause specifies the outer join in each SQL statement.

Short-form syntax:

SELECT * FROM {oj T1 LEFT OUTER JOIN T2 ON T1.C1=T2.C3}
        WHERE T1.C2>20

Long-form syntax:

SELECT * FROM
     --(*vendor(Microsoft),product(ODBC) oj
        T1 LEFT OUTER JOIN T2 ON T1.C1=T2.C3*)--

        WHERE T1.C2>20

Important: Not all servers support outer join. To determine if the current server supports outer joins, call SQLGetInfo() twice, first with the InfoType argument set to SQL_OUTER_JOINS, and then with the InfoType argument set to SQL_OJ_CAPABILITIES.