Rgding ORA-04091:table PURCHSE_DTL is mutating,trigger/function maynot c it

Question

I wrote a trigger 'TRG_PURCHASE_DTL' to update the stock table 'BRANCH_ITEM_STOCK' based on the DML actions perfomed on tables PURCHASE_DTL and ISSUE_DTL, but I am getting following error:-
ORA-04091: table PURCHASE_DTL is mutating, trigger/function may not see it
and the value of 'BRANCH_ITEM_STOCK.purchase_qty' is updated to 10 instead of 18.
The table structure and data is given below:
-- ============================================================
-- Table: BRANCH_ITEM_STOCK
-- ============================================================
create table BRANCH_ITEM_STOCK
BRANCH_CODE NUMBER(6) not null,
ITEM_CODE NUMBER(6) not null,
PURCHASE_QTY NUMBER(6) null ,
RECEIPT_QTY NUMBER(6) null ,
ISSUE_QTY NUMBER(6) null ,
BALANCE_QTY NUMBER(6) null ,
REMARKS VARCHAR2(100) null ,
constraint PK_RA25_BRANCH_ITEM_STOCK primary key (BRANCH_CODE, ITEM_CODE)
-- ============================================================
-- Table: PURCHASE_MST
-- ============================================================
create table PURCHASE_MST
BRANCH_CODE NUMBER(6) not null,
PURCHASE_YR NUMBER(6) not null,
PURCHASE_NO NUMBER(6) not null,
PURCHASE_DT DATE not null,
QUOTATION_NO NUMBER(6) not null,
QUOTATION_YR NUMBER(4) not null,
VENDOR_CODE NUMBER(6) not null,
RECEIPT_NO VARCHAR2(25) null ,
constraint PK_PURCHASE_HDR primary key (BRANCH_CODE, PURCHASE_YR, PURCHASE_NO)
-- ============================================================
-- Table: PURCHASE_DTL
-- ============================================================
create table PURCHASE_DTL
BRANCH_CODE NUMBER(6) not null,
PURCHASE_YR NUMBER(6) not null,
PURCHASE_NO NUMBER(6) not null,
REC_SNO NUMBER(6) not null,
ITEM_CODE NUMBER(6) not null,
ITEM_QTY NUMBER(6) not null,
ITEM_PRICE NUMBER not null,
ITEM_AMT NUMBER not null,
constraint PK_PURCHASE_DTL primary key (BRANCH_CODE, PURCHASE_YR, PURCHASE_NO, REC_SNO)
-- ============================================================
-- Table: ISSUE_MST
-- ============================================================
create table ISSUE_HDR
BRANCH_CODE NUMBER(6) not null,/* Issued from Branch*/
ISSUE_YR NUMBER(6) not null,
ISSUE_NO NUMBER(6) not null,
ISSUE_DT DATE not null,
ISSUED_BY VARCHAR2(15) not null,
ISSUED_TO_BRANCH VARCHAR2(15) not null,
ISSUE_STATUS NUMBER(6) null,
constraint PK_ISSUE_HDR primary key (BRANCH_CODE, ISSUE_YR, ISSUE_NO)
-- ============================================================
-- Table: ISSUE_DTL
-- ============================================================
create table ISSUE_DTL
BRANCH_CODE NUMBER(6) not null,
ISSUE_YR NUMBER(6) not null,
ISSUE_NO NUMBER(6) not null,
REC_SNO VARCHAR2(25) not null,
ITEM_CODE NUMBER(6) not null,
ITEM_DTL VARCHAR2(400) null ,
ITEM_QTY NUMBER(6) null ,
RECEIPT_QTY NUMBER(6) null ,
constraint PK_RA25_ISSUE_DTL primary key (BRANCH_CODE, ISSUE_YR, ISSUE_NO, REC_SNO)
Assume that the Contents of PURCHASE_MST is as follows:
SELECT branch_code, purchase_yr, purchase_no FROM PURCHASE_HDR;
BRANCH_CODE PURCHASE_YR PURCHASE_NO     
100          2008          1     
100          2009          1     
100          2009          2     
Now I tried to insert follwing values to the PURCHASE_DTL table:
insert into purchase_dtl (BRANCH_CODE,PURCHASE_YR,PURCHASE_NO,rec_sno,
ITEM_CODE,item_QTY)
Values (100,2008,1,1,4,5)
insert into purchase_dtl (BRANCH_CODE,PURCHASE_YR,PURCHASE_NO,rec_sno,
ITEM_CODE,item_QTY)
Values (100,2009,1,1,4,2)
insert into purchase_dtl (BRANCH_CODE,PURCHASE_YR,PURCHASE_NO,rec_sno,
ITEM_CODE,item_QTY)
Values (100,2009,2,1,4,6)
commit
Now Contents of table ' PURCHASE_DTL ' is as follows:
BRANCH_CODE PURCHASE_YR PURCHASE_NO     REC_SNO ITEM_CODE     ITEM_QTY
100          2008          1     1          4     5
100          2009          1     1          4     2
100          2009          2     1          4     6
I want to write a trigger which will insert/update/delete data into/from BRANCH_ITEM_STOCK,
so that the contents of column Purchase_qty of table BRANCH_ITEM_STOCK should be as follows:
BRANCH_CODE     ITEM_CODE     PURCHASE_QTY     RECEIPT_QTY     ISSUE_QTY     BALANCE_QTY
100          4          13          0          0          13
[Note:  i.e BRANCH_ITEM_STOCK.PURCHASE_QTY = SUM(PURCHASE_DTL.item_qty) 
     where PURCHASE_DTL.branch_code=100
     AND PURCHASE_DTL.item_code=4
Now run the following update statement.
update purchase_dtl
set item_qty= 10
where BRANCH_code=100
and purchase_yr in ( 2008) and purchase_no =1 and rec_sno = 1 AND item_code = 4
commit
Now the actual contents of column Purchase_qty of table BRANCH_ITEM_STOCK should be updated as follows:
BRANCH_CODE     ITEM_CODE     PURCHASE_QTY     RECEIPT_QTY     ISSUE_QTY     BALANCE_QTY
100          4          18          0          0          18
But I am facing problem here. I am getting following error:-
ORA-04091: table PURCHASE_DTL is mutating, trigger/function may not see it
and the value of purchase qty is updated to 10 instead of 18
Similarly if any issue of items happen (for eg:- issue_qty=2 to branch_code 200), then the purchase_qty =18,issue_qty=2 , balance_qty:=18-2=16 .
So for branch_code 200 , receipt_qty = 2.
Pls help me how to achieve the above .
Source code which I tried is given below : (but confused at the end )..please help
CREATE OR REPLACE TRIGGER trg_purchase_dtl
BEFORE INSERT ON PURCHASE_DTL
for each row
declare
-- local variables here
l_qty number(6);
l_cnt NUMBER;
BEGIN
BEGIN
SELECT COUNT(*) into l_cnt
FROM BRANCH_item_stock b
WHERE b.BRANCH_code = :new.BRANCH_code
AND b.item_code = :new.item_code ;
dbms_output.put_line('1.after selet cnt= '||l_cnt);
EXCEPTION when no_data_found then
l_cnt := 0;
dbms_output.put_line('2.in expt NDF selet cnt= '||l_cnt);
null;
END;
IF INSERTING THEN
dbms_output.put_line('3.before if ...going to insert ');
IF l_cnt = 0 THEN
dbms_output.put_line('hihhiii.......lcnt=0...item_code='||:old.item_code||'~l_qty='||l_qty);
IF INSERTING THEN
     INSERT INTO BRANCH_ITEM_STOCK
(BRANCH_code,Item_Code, PURCHASE_QTY,RECEIPT_QTY, issue_qty, balance_qty)
     VALUES(:NEW.BRANCH_code,:NEW.Item_Code, :NEW.ITEM_QTY,0, 0, 0);
END IF;
ELSIF l_cnt >0 THEN
SELECT purchase_qty into l_qty
FROM BRANCH_Item_Stock
WHERE BRANCH_code = :new.BRANCH_code
AND item_code = :new.item_code ;
l_qty := l_qty + :NEW.ITEM_QTY;
dbms_output.put_line('6.after selet qty= '||l_qty ||'~new qty='||:NEW.ITEM_QTY||'~old qty='||:OLD.ITEM_QTY);
dbms_output.put_line('7.before update '||l_qty);
-- IF INSERTING OR UPDATING THEN
UPDATE BRANCH_ITEM_STOCK
          SET PURCHASE_QTY = l_qty
          WHERE BRANCH_code = :new.BRANCH_code
AND item_code = :new.item_code ;
dbms_output.put_line('8.after update= '||l_qty);
--END IF;
END IF;
END IF; -- end of INSERTING
-- END;
--EXCEPTION WHEN DUP_VAL_ON_INDEX THEN
     IF UPDATING THEN
          dbms_output.put_line('9.if UPDATING...qty= '||l_qty ||'~new qty='||:NEW.ITEM_QTY||'~old qty='||:OLD.ITEM_QTY);
BEGIN
dbms_output.put_line('~old unotcode='||:old.BRANCH_code||'~old.item_code='||:OLD.ITEM_CODE||'~old itemqty='||:old.item_qty);
dbms_output.put_line('~new unotcode='||:new.BRANCH_code||'~new.item_code='||:new.ITEM_CODE||'~new itemqty='||:new.item_qty);
SELECT NVL(SUM(item_qty), 0) into l_qty
     FROM Ra25_Purchase_Dtl
     WHERE BRANCH_code IN ( :old.BRANCH_code )
     AND item_code in ( :old.item_code)
     AND item_qty <> :old.item_code ;
EXCEPTION WHEN OTHERS THEN
dbms_output.put_line('10.in EWO'||sqlerrm);
END;
--l_qty := l_qty + :NEW.ITEM_QTY;         
dbms_output.put_line('11.after selet qty= '||l_qty ||'~new qty='||:NEW.ITEM_QTY||'~old qty='||:OLD.ITEM_QTY);
     UPDATE BRANCH_ITEM_STOCK
          SET PURCHASE_QTY = l_qty      --:new.item_qty
          WHERE BRANCH_code = :old.BRANCH_code
          AND item_code = :old.item_code ;
          dbms_output.put_line('13.after update ');
     END IF;
IF DELETING THEN
DELETE FROM BRANCH_ITEM_STOCK
WHERE BRANCH_CODE = :OLD.BRANCH_code
AND ITEM_CODe = :OLD.item_code;
END IF;
end trg_purchase_dtl;
Please help me how to resolve this problem asap.
-------------------------------------------------------------------------------------------------------------------------------------------------

Answer 1

Hi,
Welcome to the forum!
See this thread [Avoiding Mutating Tables|http://asktom.oracle.com/tkyte/Mutate/index.html]
Tip: to preserve formatted code enclose it between {noformat}{noformat} tags (start and end tags are the same) :)
Thank you for posting DDL and DML of basic data, all people that post should follow this approach.
Regards,