URGENT : Trigger with Mutating Error

Question

Hi,
I'm trying to write a trigger on a Table ROOM_BLOCK to update a value in table ROOM_OOI_OOS.
As given below, which works perfectly.
BEGIN
IF INSERTING THEN
IF NVL(:NEW.ROOM_OOI_OOS_ID,0) <> 0 THEN
UPDATE ROOM_OOI_OOS SET NO_OF_ROOMS = NVL(NO_OF_ROOMS,0)+1
WHERE ROOM_OOI_OOS_ID = :NEW.ROOM_OOI_OOS_ID;
END IF;
ELSIF UPDATING THEN
IF NVL(:OLD.ROOM_OOI_OOS_ID,0) <> 0 THEN
UPDATE ROOM_OOI_OOS SET NO_OF_ROOMS = NVL(NO_OF_ROOMS,0)-1
WHERE ROOM_OOI_OOS_ID = :OLD.ROOM_OOI_OOS_ID;
END IF;
IF NVL(:NEW.ROOM_OOI_OOS_ID,0) <> 0 THEN
UPDATE ROOM_OOI_OOS SET NO_OF_ROOMS = NVL(NO_OF_ROOMS,0)+1
WHERE ROOM_OOI_OOS_ID = :NEW.ROOM_OOI_OOS_ID;
END IF;
ELSE
IF NVL(:OLD.ROOM_OOI_OOS_ID,0) <> 0 THEN
UPDATE ROOM_OOI_OOS SET NO_OF_ROOMS = NVL(NO_OF_ROOMS,0)-1
WHERE ROOM_OOI_OOS_ID = :OLD.ROOM_OOI_OOS_ID;
END IF;
END IF;
END;
But when I add a select statement. the trigger seems to fail with a mutating error ORA-04091
and Error at Line which executes the statement immidiate ORA-04088.
DECLARE
stmt VARCHAR2(500);
vcount INTEGER;
BEGIN
IF INSERTING THEN
--INSERT INTO SHRUTI_TEST (DESCR) VALUES ('Inserting');
IF NVL(:NEW.ROOM_OOI_OOS_ID,0) <> 0 THEN
stmt := 'Select count(*) from ROOM_BLOCK ' ||
' WHERE ROOM_OOI_OOS_ID = ' || :NEW.ROOM_OOI_OOS_ID ||
' AND ROOM_NO = ''' || :NEW.ROOM_NO || ''' ';
EXECUTE IMMEDIATE stmt INTO vcount;
IF vcount = 1 THEN
UPDATE ROOM_OOI_OOS SET NO_OF_ROOMS = NVL(NO_OF_ROOMS,0)+1
WHERE ROOM_OOI_OOS_ID = :NEW.ROOM_OOI_OOS_ID;
END IF;
END IF;
ELSIF UPDATING THEN
IF NVL(:OLD.ROOM_OOI_OOS_ID,0) <> 0 THEN
UPDATE ROOM_OOI_OOS SET NO_OF_ROOMS = NVL(NO_OF_ROOMS,0)-1
WHERE ROOM_OOI_OOS_ID = :OLD.ROOM_OOI_OOS_ID;
END IF;
IF NVL(:NEW.ROOM_OOI_OOS_ID,0) <> 0 THEN
UPDATE ROOM_OOI_OOS SET NO_OF_ROOMS = NVL(NO_OF_ROOMS,0)+1
WHERE ROOM_OOI_OOS_ID = :NEW.ROOM_OOI_OOS_ID;
END IF;
ELSE
IF NVL(:OLD.ROOM_OOI_OOS_ID,0) <> 0 THEN
UPDATE ROOM_OOI_OOS SET NO_OF_ROOMS = NVL(NO_OF_ROOMS,0)-1
WHERE ROOM_OOI_OOS_ID = :OLD.ROOM_OOI_OOS_ID;
END IF;
END IF;
END;
Please tell me how to solve this problem...
Regards
Mike.

Answer 1

Thank you for your reply to my posting.
I researched and used your recommendation. I was
wondering if you can help me resolve the following two
problems.
Table kassa1 has NAME and AGE columns. Table Kassa2
has one column Age.
I have created the following trigger. It keeps
raising a ORA-06519 : Active autonomous transaction
detected and rolled back error.
Create or replace trigger Name_Age_Row after insert or
update on Kassa1
For each row
Declare
Total_Age VARCHAR(8);
PRAGMA AUTONOMOUS_TRANSACTION;
BEGIN
     Select SUM(Age) into Total_Age from Kassa1;
     insert into kassa2 values(Total_aAge);
End;     
The following trigger also generates ORA-00036:
Maximum number of recursive SQL levels(50) exceeded
error.
Create or replace trigger Name_Age_Row after insert or
update on Kassa1
For each row
Declare
PRAGMA AUTONOMOUS_TRANSACTION;
BEGIN
     insert into kassa1 values('newname', 'newage');
End;