The RESULT clause is optional in procedures. Omitting the result clause allows you to write procedures that return different result sets, with different numbers or types of columns, depending on how they are executed.
If you do not use the variable result sets feature, you should use a RESULT clause for performance reasons.
For example, the following procedure returns two columns if the input variable is Y, but only one column otherwise:
CREATE PROCEDURE Names( IN formal char(1) ) BEGIN IF formal = 'y' THEN SELECT Surname, GivenName FROM Employees ELSE SELECT GivenName FROM Employees END IF END;
The use of variable result sets in procedures is subject to some limitations, depending on the interface used by the client application.
Embedded SQL You must DESCRIBE the procedure call after the cursor for the result set is opened, but before any rows are returned, in order to get the proper shape of result set.
For more information about the DESCRIBE statement, see DESCRIBE statement [Interactive SQL].
ODBC Variable result set procedures can be used by ODBC applications. The SQL Anywhere ODBC driver performs the proper description of the variable result sets.
Open Client applications Open Client applications can use variable result set procedures. SQL Anywhere performs the proper description of the variable result sets.