Stored procedures with return code

SQL Server stored procedures can return integer values. To get the return value of a stored procedure, you must use an assignment expression in the ODBC call escape sequence:

PREPARE stmt FROM "{ ? = call proc3(?,?,?) }"

Then the statement can be executed with the EXECUTE instruction, by specifying the output parameter receiving the returned value as first element in the USING list, with the OUT modifier:

MAIN
    DEFINE p1, p2, r INTEGER
    CONNECT TO ...
    WHENEVER ERROR CONTINUE
    EXECUTE IMMEDIATE "DROP PROCEDURE p_mul"
    WHENEVER ERROR STOP
    EXECUTE IMMEDIATE "CREATE PROCEDURE p_mul ( @p1 INT, @p2 INT )
     AS BEGIN
     DECLARE @r INT
     SET @r = @p1 * @p2;
     RETURN @r;
     END"
    LET p1 = 15
    LET p2 = 3
    PREPARE s1 FROM "{ ? = call p_mul(?,?) }"
    EXECUTE s1 USING r OUT, p1 IN, p2 IN
    DISPLAY "r = ", r
END MAIN