Input -

Scenario1 - Declare the cursor for updating column manager_id of employee_details table.

DECLARE CURSOR -

   EXEC SQL 
	DECLARE E1 CURSOR FOR
     	SELECT EMP_NAME,
               MANAGER_ID
     	FROM   EMPLOYEE_DETAILS
        FOR    UPDATE OF MANAGER_ID
   END-EXEC.

UPDATE -

   EXEC SQL 
	UPDATE EMPLOYEE_DETAILS
	SET    MANAGER_ID = :WS-MANAGER-ID		   
	WHERE  CURRENT OF E1
   END-EXEC.

Scenario2 - Declare the cursor for deleting all columns of the employee_details table.

DECLARE CURSOR -

   EXEC SQL 
	DECLARE E2 CURSOR FOR
     	SELECT EMP_ID,
               EMP_NAME,
               DESIGNATION,
               MANAGER_ID,
               DATE_OF_HIRE,
               SALARY,
               DEPT_ID
     	FROM   EMPLOYEE_DETAILS 
     	FOR UPDATE 
   END-EXEC. 
   
DELETE -

   EXEC SQL 
	DELETE FROM EMPLOYEE_DETAILS
	WHERE  CURRENT OF E2
   END-EXEC. 

Scenario3 - Declare the cursor for updating designation "FRESHER" in department 1000 of employee_details table.

DECLARE CURSOR -
   EXEC SQL 
	DECLARE E3 CURSOR FOR
     	SELECT EMP_ID,
               EMP_NAME,
               DESIGNATION
     	FROM   EMPLOYEE_DETAILS 
     	WHERE  DESIGNATION = "FRESHER"
		AND    DEPT_ID = 1000
     	FOR    UPDATE OF DESIGNATION 
   END-EXEC.  
   
UPDATE -

   EXEC SQL 
	UPDATE EMPLOYEE_DETAILS
	SET    DESIGNATION = "JUNIOR DEVELOPER"	
	WHERE  CURRENT OF E3
   END-EXEC.

Scenario4 - Declare the cursor for updating designation "FRESHER" in departments 1000 and 2000 of the employee_details table.

DECLARE CURSOR -
   EXEC SQL 
	DECLARE E4 CURSOR FOR
     	SELECT EMP_ID,
               EMP_NAME,
               DESIGNATION
     	FROM   EMPLOYEE_DETAILS 
     	WHERE  DESIGNATION = "FRESHER"
		AND    DEPT_ID IN (1000, 2000)
		ORDER  BY DEPT_ID ASC
     	FOR    UPDATE OF DESIGNATION 
   END-EXEC. 
   
UPDATE -

   EXEC SQL 
	UPDATE EMPLOYEE_DETAILS
	SET    DESIGNATION = "JUNIOR DEVELOPER"	
	WHERE  CURRENT OF E4
   END-EXEC.

Practical Example -

Scenario - The below example describes how the update cursor is coded in the COBOL + DB2 program.

Requirement - Hike the salary of TESTER(s) by 3000.

UPDATE CURSOR Example Code -

----+----1----+----2----+----3----+----4----+----5----+
       IDENTIFICATION DIVISION.
       PROGRAM-ID. CUPDATE.

       ENVIRONMENT DIVISION.
       DATA DIVISION.
       WORKING-STORAGE SECTION.

           EXEC SQL
             INCLUDE SQLCA 
           END-EXEC.

           EXEC SQL
             INCLUDE EMPLDET
           END-EXEC.

      * DECLARING UPDATE   CURSOR
           EXEC SQL
                DECLARE CSR1 CURSOR FOR
                SELECT EMP_ID,
                       EMP_NAME,
                       DESIGNATION,
                       MANAGER_ID,
                       SALARY
                FROM   EMPLOYEE_DETAILS
                WHERE  DESIGNATION = 'TESTER'
                  AND  DEPT_ID = 2000
                FOR    UPDATE OF SALARY 
           END-EXEC.

        01 WS-VAR.
           05 WS-UCNT          PIC 9(02) VALUE ZEROES.
           05 WS-UPDATED-SAL   PIC S9(5)V9(2) USAGE COMP-3.

       PROCEDURE DIVISION. 
	   
      * OPENING CURSOR
           EXEC SQL 
                OPEN CSR1
           END-EXEC.
 
      * FETCHING CURSOR LOOP UNTIL END OF RESULT TABLE
           IF SQLCODE EQUAL ZERO
              PERFORM FETCH-EMP-DETAILS
                 THRU FETCH-EMP-DETAILS-EXIT
                UNTIL SQLCODE NOT EQUAL 0 
           END-IF.

      * CLOSING CURSOR
           EXEC SQL
                CLOSE CSR1
           END-EXEC.
  
           DISPLAY "NO OF ROWS UPDATED:  ", WS-UCNT.

           STOP RUN.

       FETCH-EMP-DETAILS.

      * FETCH CURSOR  
           EXEC SQL
                FETCH CSR1
                INTO   :EMP-ID, 
                       :EMP-NAME,
                       :DESIGNATION,
                       :MANAGER-ID
                       :MANAGER-ID-NI,
                       :SALARY 
           END-EXEC.

           EVALUATE SQLCODE
               WHEN ZERO
                    PERFORM UPDATE-EMP-DETAILS
                       THRU UPDATE-EMP-DETAILS-EXIT
               WHEN 100
                    CONTINUE
               WHEN OTHER
                    DISPLAY "DB2 ERROR:  ", SQLCODE
           END-EVALUATE.

       FETCH-EMP-DETAILS-EXIT.
           EXIT.
 
       UPDATE-EMP-DETAILS.

           COMPUTE WS-UPDATED-SAL = SALARY + 3000. 

           EXEC SQL
                UPDATE EMPLOYEE_DETAILS
                   SET SALARY = :WS-UPDATED-SAL 
                 WHERE CURRENT OF CSR1
           END-EXEC.

           EVALUATE SQLCODE
               WHEN ZERO
                    COMPUTE WS-UCNT = WS-UCNT + 1 
               WHEN 100 
                    DISPLAY "UPDATING ROW NOT FOUND" 
               WHEN OTHER
                    DISPLAY "DB2 ERROR:  ", SQLCODE 
           END-EVALUATE.

       UPDATE-EMP-DETAILS-EXIT.
           EXIT.

Output -

employee_details table after UPDATE -

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