为什么没有触发异常NO_DATA_FOUND？

Question

So the problem i am having is that if i execute the following procedure and the cursor doesnt find the parameter being passed, it continues to execute the block (insert statement) but instead of throwing the NO_DATA_FOUND exception error it throws a parent/foreign key error.

CREATE OR REPLACE PACKAGE ASSIGNMENT3 IS

PROCEDURE END_CAMPAIGN(CTITLE IN CAMPAIGN.CAMPAIGNTITLE%TYPE);

END ASSIGNMENT3;
/    

CREATE OR REPLACE PACKAGE BODY ASSIGNMENT3 AS    
    PROCEDURE END_CAMPAIGN(CTITLE IN CAMPAIGN.CAMPAIGNTITLE%TYPE) IS
        CURSOR ADCOST_CUR IS
        SELECT ACTUALCOST
        FROM ADVERTISEMENT
        WHERE ADVERTISEMENT.CAMPAIGNTITLE = CTITLE;
        V_TOTALCOST NUMBER;

        BEGIN
        V_TOTALCOST := 0;
          FOR INVOICE_REC IN ADCOST_CUR
          LOOP
            V_TOTALCOST := V_TOTALCOST + INVOICE_REC.ACTUALCOST;
          END LOOP;
          INSERT INTO INVOICE(INVOICENO, CAMPAIGNTITLE, DATEISSUED, DATEPAID, BALANCEOWING, STATUS)
          VALUES (AUTOINCREMENTINVOICE.nextval, CTITLE, SYSDATE, NULL,V_TOTALCOST,NULL);
            EXCEPTION WHEN NO_DATA_FOUND THEN
              DBMS_OUTPUT.PUT_LINE('ERROR:The campaign title you entered returned no record(s), please enter a valid campaign title.');
        COMMIT;
        END END_CAMPAIGN;


        END ASSIGNMENT3;
        /


        SET SERVEROUTPUT ON
        EXECUTE ASSIGNMENT3.END_CAMPAIGN('Panasonic 3D TV');

While the parent foreign key error is correct, i dont want the block to execeute if the cursor doesnt return a row. Why is this happening?

Also, in terms of placing the COMMIT, where exactly do i tell it to COMMIT? Before the exception or after?

This is for a uni assignment.

Answer 1

When you loop over a cursor like that, if the cursor finds no matching rows, the loop simply doesn't execute at all. A NO_DATA_FOUND exception would only be raised if you had a SELECT ... INTO ... statement inside the BEGIN/END block that did not return any rows.

Where you have the COMMIT placed now, it is part of the EXCEPTION block -- but your indentation implies that you want it to execute whether the exception occurred or not. In this case, I would just put the COMMIT immediately after the INSERT, since it only matters if the INSERT is successful.

Answer 2

"So is there no way to have the NODATAFOUND exception trigger when using a cursor, if the CTITLE parameter isnt found in the table"

What you could do is test the value of V_TOTAL_COST. If it is zero raise an exception, like this:

PROCEDURE END_CAMPAIGN(CTITLE IN CAMPAIGN.CAMPAIGNTITLE%TYPE) IS
    CURSOR ADCOST_CUR IS
    SELECT ACTUALCOST
    FROM ADVERTISEMENT
    WHERE ADVERTISEMENT.CAMPAIGNTITLE = CTITLE;
    V_TOTALCOST NUMBER;

    BEGIN
      V_TOTALCOST := 0;
      FOR INVOICE_REC IN ADCOST_CUR
      LOOP
        V_TOTALCOST := V_TOTALCOST + INVOICE_REC.ACTUALCOST;
      END LOOP;

      if v_total_cost = 0 then
          raise no_data_found;
      end if;

      INSERT INTO INVOICE(INVOICENO, CAMPAIGNTITLE, DATEISSUED, DATEPAID, BALANCEOWING, STATUS)
      VALUES (AUTOINCREMENTINVOICE.nextval, CTITLE, SYSDATE, NULL,V_TOTALCOST,NULL);
      COMMIT;
    EXCEPTION WHEN NO_DATA_FOUND THEN
          DBMS_OUTPUT.PUT_LINE('ERROR:The campaign title you entered returned no record(s), please enter a valid campaign title.');

    END END_CAMPAIGN;

This assumes you have a business rule that ACTUAL_COST cannot be zero.

Alternatively, there is the clunkier workaround of incrementing a counter in the loop and testing whether it is zero after the loop.

Answer 3

As for where to place the commit I would say the answer is not inside the procedure . The client (sqlplus in this case) should determine if the transaction will commit or rollback as the call to end the campaign may be just a part of a wider process. Also assuming that a campaign can exist without any advertisements then I would have an explicit check that the campaign title is valid perhaps against the table of CAMPAIGN? as suggested below:

CREATE OR REPLACE PACKAGE ASSIGNMENT3 IS

    PROCEDURE END_CAMPAIGN(CTITLE IN CAMPAIGN.CAMPAIGNTITLE%TYPE);

END ASSIGNMENT3;
/   

CREATE OR REPLACE PACKAGE BODY ASSIGNMENT3 AS    
    PROCEDURE END_CAMPAIGN(CTITLE IN CAMPAIGN.CAMPAIGNTITLE%TYPE) IS

        V_VALID_CAMPAIGN INTEGER; 
        V_TOTALCOST NUMBER;

    BEGIN

        -- Check this campaign title is valid 
        /* Will get you NO_DATA_FOUND here if CTITLE is invalid so wrap in 
           another BEGIN END block to throw own custom error that the client 
           of this procedure can handle (if it wants) */
        BEGIN 
            SELECT 1 
            INTO V_VALID_CAMPAIGN 
            FROM CAMPAIGN
            WHERE CAMPAIGNTITLE = CTITLE;
        EXCEPTION
            WHEN NO_DATA_FOUND THEN 
                RAISE_APPLICATION_ERROR(-20000,'The campaign title you entered returned no record(s), please enter a valid campaign title.'); 
        END;

        -- Now tot up the cost of ads in this campaign and raise the invoice
        SELECT SUM(ACTUALCOST)
        INTO V_TOTALCOST
        FROM ADVERTISEMENT
        WHERE ADVERTISEMENT.CAMPAIGNTITLE = CTITLE;

        INSERT INTO INVOICE(INVOICENO, CAMPAIGNTITLE, DATEISSUED, DATEPAID, BALANCEOWING, STATUS)
        VALUES (AUTOINCREMENTINVOICE.nextval, CTITLE, SYSDATE, NULL,V_TOTALCOST,NULL);

    END END_CAMPAIGN;

END ASSIGNMENT3;
/

EXECUTE ASSIGNMENT3.END_CAMPAIGN('Panasonic 3D TV');
COMMIT;