Help with mutating trigger

Question

Hi all,
I have a trigger shown below is gives me the mutating error.
The error is to do with the select from the payments table (which it does not allow cos of the mutating effect).
Can anyone give me some ideas on how I can resolve this?
Thank you very much
create or replace
TRIGGER CHECK_INVOICE_PAID_IN_FULL AFTER
UPDATE OF "PAYMENT_STATUS" ON "PAYMENTS" FOR EACH ROW
DECLARE
-- check if all the payments for that invoice have been received (completed)
-- if they are complete then sum all the payments for that invoice and compare to gross value on invoices
v_invoice_amount NUMBER;
v_gross_amount NUMBER;
thisproc CONSTANT VARCHAR2(80) := 'trap_errmesg for mco_transfer_status';
v_value VARCHAR2(150);
BEGIN
-- Changed as requested by nicola on 12/09/05 IF :NEW.PAYMENT_COMPLETE is not null
IF :NEW.PAYMENT_STATUS='C' AND :NEW.PAYMENT_STATUS <> :OLD.PAYMENT_STATUS
THEN
-- We will sum all the payments for that invoice that have a value in payment_complete
SELECT NVL(SUM(amount),0) INTO v_invoice_amount FROM payments WHERE payment_complete IS NOT NULL AND invoice_id=:NEW.INVOICE_ID;
-- We will also get the gross amount for the invoice to compare to the sum of the payments
SELECT NVL(gross,0) INTO v_gross_amount FROM invoices WHERE
invoice_id = :NEW.INVOICE_ID ;
END IF;
IF v_invoice_amount = v_gross_amount
THEN
UPDATE invoices SET paid_date=SYSDATE;
END IF;
END CHECK_INVOICE_PAID_IN_FULL;
/

Answer 1

Hi Anwar,
Thanks for this.
Can you please help me out here
I did the bit with creating a temporay table to hold the invoice_ids and then created a procedure that will be fired by the trigger, however because of the clause
IF :NEW.PAYMENT_STATUS='C' AND :NEW.PAYMENT_STATUS <> :OLD.PAYMENT_STATUS
I cant use a statement level trigger for this procedure and when i use the row level trigger i get the mutating error.
here is what i have got so far.
A temporary table which holds the invoice_ids (this is called payments_temp)
I then created a trigger as below which populates this temp table
TRIGGER insert_payments_temp BEFORE
UPDATE OF "PAYMENT_STATUS" ON "PAYMENTS" FOR EACH ROW
DECLARE
-- check if all the payments for that invoice have been received (completed)
-- if they are complete then sum all the payments for that invoice and compare to gross value on invoices
v_invoice_amount NUMBER;
v_gross_amount NUMBER;
thisproc CONSTANT VARCHAR2(80) := 'trap_errmesg for mco_transfer_status';
v_value VARCHAR2(150);
BEGIN
INSERT INTO payments_temp
VALUES (:NEW.invoice_id);
END insert_payments_temp;
Then I created a procedure below which will do the update
PROCEDURE "CHECK_INVOICE_PAID_IN_FULL_PRO" IS
-- check if all the payments for that invoice have been received (completed)
-- if they are complete then sum all the payments for that invoice and compare to gross value on invoices
v_invoice_amount NUMBER(20);
v_gross_amount NUMBER;
thisproc CONSTANT VARCHAR2(80) := 'trap_errmesg for mco_transfer_status';
v_value VARCHAR2(150);
BEGIN
-- We will sum all the payments for that invoice that have a value in payment_complete
--select sum(amount) into v_invoice_amount from payments where payment_complete is not null and invoice_id=:NEW.INVOICE_ID;
FOR x IN (SELECT invoice_id FROM payments_temp) LOOP
SELECT NVL(SUM(amount),0) INTO v_invoice_amount FROM payments
WHERE payment_complete IS NOT NULL AND invoice_id=X.INVOICE_ID;
SELECT NVL(gross,0) INTO v_gross_amount FROM INVOICES WHERE
invoice_id = X.INVOICE_ID ;
END LOOP;
-- We will also get the gross amount for the invoice to compare to the sum of the payments
IF v_invoice_amount = v_gross_amount
THEN
UPDATE INVOICES SET paid_date=SYSDATE;
COMMIT;
END IF;
END CHECK_INVOICE_PAID_IN_FULL_PRO;
Then finally the update trigger itself below
TRIGGER "NICKC"."CHECK_INVOICE_PAID_IN_FULL" AFTER
UPDATE OF "PAYMENT_STATUS" ON "NICKC"."PAYMENTS" FOR EACH ROW
DECLARE
-- check if all the payments for that invoice have been received (completed)
-- if they are complete then sum all the payments for that invoice and compare to gross value on invoices
v_invoice_amount NUMBER;
v_gross_amount NUMBER;
thisproc CONSTANT VARCHAR2(80) := 'trap_errmesg for mco_transfer_status';
v_value VARCHAR2(150);
BEGIN
-- Changed as requested by nicola on 12/09/05 IF :NEW.PAYMENT_COMPLETE is not null
IF :NEW.PAYMENT_STATUS='C' AND :NEW.PAYMENT_STATUS <> :OLD.PAYMENT_STATUS
THEN
CHECK_INVOICE_PAID_IN_FULL_PRO;
END IF;
END CHECK_INVOICE_PAID_IN_FULL;
However i still get the mutating error message and when i try to create a statemtnet level trigger i get the message say cannot use :NEW and :OLD values here.
Please help