1. In this module, we will design a program to work with the PROJECT table, learning to insert a new project into the table, to delete one or more projects from the table, and to update project information in the table. You add, delete, or modify information from a table with the standard SQL INSERT, DELETE, and UPDATE commands.

2. :. : : : : : : : DATA DIVISION. If we are going to be working FILE SECTION. with the PROJECT table, this WORKING STORAGE SECTION. table must be declared... EXEC SQL INCLUDE SQLCA END-EXEC. EXEC SQL INCLUDE PROJECT END-EXEC. This INCLUDE PROJECT statement PROCEDURE DIVISION. declares the PROJECT table, and : : : : : : : : : : it declares a set of local vari- : : · ables which match the table. ·

3. PROJECT TABLE +-------------------------------------------------------------------+ ¦ PROJNO ¦ PROJNAME ¦DEPTNO¦ LEADER ¦ ¦------------+----------------------------+-----------+------------+ ¦ 111111 ¦ Accounts Receivable ¦ 200 ¦ 106321 ¦ ¦ 222222 ¦ Marketing Analysis ¦ 300 ¦ 220025 ¦ ¦ 333333 ¦ Customer Survey Project ¦ 300 ¦ 110440 ¦ ¦ 444444 ¦ Financial Reporting ¦ 100 ¦ 155775 ¦ ¦ 555555 ¦ PC Local Area Networks ¦ 500 ¦ 233177 ¦ +-------------------------------------------------------------------+ Let's assume that you have been told that a new project must be added to the PROJECT table, but there is no program set up to do this. We will develop a program to add one row of data to the PROJECT table...

4. :. : : : : : : : PROCEDURE DIVISION. PERFORM 100-GET-SCREEN. PERFORM 200-VALID-CHK. EXEC SQL INSERT INTO PROJECT (PROJNO,PROJNAME,DEPTNO, LEADER) VALUES (:PJ-NO, :PJ-NAME, :DP-NO, :PJ-LDR) END-EXEC. : : : : : : : · ·

5. To insert a number of rows from another DB2 table, the columns list and VALUES list may be replaced by a subselect. DELETE works much the same EXEC SQL DELETE FROM PROJECT WHERE DEPTNO = :DP-NO END-EXEC. The syntax for UPDATE in embedded SQL is: EXEC SQL UPDATE table_name SET column_name = :host-name, column_name = :host-name WHERE expression END-EXEC.

6. Data for the columns are stored in the the following host variables. PROJNAME in :PJ-NAME LEADER in :PJ-LDR PROJNO in :PJ-NO DEPTNO in :DP-NO Complete the code that will update the project name, department number, and leader for the requested project number. · EXEC SQL UPDATE PROJECT SET PROJNAME = :PJ-NAME, DEPTNO = :DP-NO, LEADER = :PJ-LDR WHERE PROJNO = :PJ-NO END-EXEC.

7. Error Handling in embedded SQL statements is straightforward because DB2 returns a result code to the SQLCA after every SQL statement is executed. Which field would you look in to determine if a system error has occurred? SQLWARNING SQLCODE SQLERROR SQLCA

8. There are three classes of codes in the SQLCODE. ------------------------------------------------ ERRORS a negative SQLCODE value indicates a program or system error. You should catch this to terminate your program or to handle the error. WARNINGS a positive SQLCODE value indicates warning conditions. They are not fatal, but they should be checked further before continuing. NOT FOUND an SQLCODE value = 100 indicates that no data satisfied a WHERE clause.

9. WHENEVER Statement ------------------ The WHENEVER statement causes the program to automatically check the SQLCODE. Based on the value it finds it takes the action you specify. There are three different WHENEVER statements: WHENEVER NOT FOUND checks for SQLCODE = 100 WHENEVER SQLWARNING checks for positive SQLCODE. WHENEVER SQLERROR checks for negative SQLCODE

10. The format of the WHENEVER statement is: ---------------------------------------- EXEC SQL WHENEVER condition action END-EXEC. The conditions are: The actions are: SQLWARNING CONTINUE SQLERROR GO TO label NOT FOUND

11. The format of the WHENEVER statement is: ---------------------------------------- WHENEVER ¦ NOT FOUND ¦ ¦ CONTINUE ¦ ¦ SQLERROR ¦ ¦ GO TO label ¦ ¦ SQLWARNING ¦ ¦ ¦ Conditions: ----------- NOT FOUND an SQLCODE value of +100 which means data-not-found. SQLERROR negative SQLCODE value indicating a serious SQL error or system error. SQLWARNING positive SQLCODE value other than +100 warning condition where SQLWARNO = 'W'. Actions: -------- CONTINUE tells SQL to go to the next sequential statement in the program. GO TO label Tells SQL to branch to the section-name and to continue processing.

12. Let's establish some error checking in our program. Assume that we have labels included in our program of: 700-CHECK-ERROR 800-CHECK-WARNING The code to check for a negative value in the SQLCODE is… PROCEDURE DIVISION. PERFORM 100-GET-SCREEN. PERFORM 200-VALID-CHK. EXEC SQL WHENEVER SQLERROR GO TO 700-CHECK-ERROR END-EXEC.

13. Code for a positive value other than +100 in the SQLCODE using the label 800-CHECK-WARNING PROCEDURE DIVISION. PERFORM 100-GET-SCREEN. PERFORM 200-VALID-CHK. EXEC SQL WHENEVER SQLERROR GO TO 700-CHECK-ERROR END-EXEC. EXEC SQL WHENEVER SQLWARNING GO TO 800-CHECK-WARNING END-EXEC.

14. Finally, we need to take action if no record is found. The value the SQLCODE will contain to indicate not found:+100 An ex. Where we check ourselves instead of using WHENEVER EXEC SQL UPDATE PROJECT SET PROJNAME = :PJ-NAME DEPTNO = :DP-NO LEADER = :PJ-LDR WHERE PROJNO = :PJ-NO END-EXEC. IF SQLCODE = +100 DISPLAY 'NO RECORD FOUND FOR' PJ-NO DISPLAY 'TABLE NOT UPDATED'.