You can return data values to an application from a procedure (although not from a procedure invoked by a rule) by using the OUTPUT option in the parameter list. To do this you must use the OUTPUT option in both the CREATE PROCEDURE and EXECUTE PROCEDURE statements. The following example shows the statement that creates such a procedure:
CREATE PROCEDURE GetName (PartNumber CHAR(16) NOT NULL,
PartName CHAR(30) NOT NULL {{OUTPUT}}) as
BEGIN
SELECT PartName INTO :PartName
FROM PurchDB.Parts
WHERE PartNumber = :PartNumber);
RETURN ::sqlcode;
END;
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The following shows how the procedure is invoked from an application program:
Host variables are declared. In this example, the host variable names are different from the parameter names used in the CREATE PROCEDURE statement.
C Declarations: COBOL Declarations:
EXEC SQL BEGIN DECLARE SECTION; EXEC SQL BEGIN DECLARE SECTION END-EXEC.
char PartNo[16]; 01 PARTNO PIC X(15).
char Part[31]; 01 PART PIC X(30).
int ReturnStatus; 01 RETCODE PIC S9(9) COMP.
EXEC SQL END DECLARE SECTION; EXEC SQL END DECLARE SECTION END-EXEC.
The application prompts for a part number, then calls the
procedure to obtain the part's name from the Parts table, as follows:
In C: In COBOL:
EXEC SQL EXECUTE PROCEDURE EXEC SQL EXECUTE PROCEDURE
:ReturnStatus=GetName :RETCODE = GETNAME (:PARTNO,
(:PartNo, :Part {{OUTPUT}}); :PART {{OUTPUT}}) END-EXEC.
if(sqlca.sqlcode==0) IF SQLCODE IS ZERO THEN
if(ReturnStatus==0) IF RETCODE IS ZERO THEN
printf("Name is %s\n", Part); DISPLAY "NAME IS " PART
END-IF.
END-IF.
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In the CREATE PROCEDURE statement, two parameters are defined and
given data types and sizes: PartNumber and PartName, which is declared for output. In the EXECUTE PROCEDURE statement, the parameters are passed to the procedure in host variables :PartNo and :Part, which is marked for OUTPUT. On a successful return from the procedure, the part name is printed out. (If your application requires an output only parameter, you can specify the ONLY option to avoid unnecessary initialization of procedure parameters.)
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 | NOTE: Be sure to test SQLCODE first and then (if desired) the return
status code before examining the data returned in OUTPUT parameters. |
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