How to write DML operation in a function

Question

Hi
Its very urgent for me.
I am writing DML operation directly in a function and is being called from select statement, it is getting error as "DML Operations cannot be performed inside a query".
How to write a DML operation inside a function.
My objective is to call that function from select statement.
Please help me out.
Thankd

Answer 1

No no no. You're committing after each row! soany
other session running the same query will see the
changes you're making. Your session will equallysee
changes caused by running this query in those
sessions.Other session, yes, but current session will only see
the changes once it has completed the current
statement. Otherwise my "rn" column would not have
gone up sequentially in the above example. it would
have gone
1st row rn = 1 (all rows get updated by 1:-
2,3,4,5,6,7,8,9,10,11)
2nd row rn = 3 (all rows get update by 1:-
3,4,5,6,7,8,9,10,11,12)
3rd row rn = 5 (all rows get update by 1:-
4,5,6,7,8,9,10,11,12,13)
4th row rn = 7 (all rows get update by 1:-
5,6,7,8,9,10,11,12,13,14)
5th row rn = 9 (all rows get update by 1:-
6,7,8,9,10,11,12,13,14,15)
6th row rn = 11 (all rows get update by 1:-
7,8,9,10,11,12,13,14,15,16)
7th row rn = 13 (all rows get update by 1:-
8,9,10,11,12,13,14,15,16,17)
8th row rn = 15 (all rows get update by 1:-
9,10,11,12,13,14,15,16,17,18)
9th row rn = 17 (all rows get update by 1:-
10,11,12,13,14,15,16,17,18,19)
10th row rn = 19 (all rows get update by 1:-
11,12,13,14,15,16,17,18,19,20)
So the fact the commit happens each time the rows get
updated, isn't effecting the currently running select
statement.
No, actually you DO see the other session changes. This is because it is AUTONOMOUS transaction, and this a function.
Test by adding:
create or replace function incvals return number as
pragma autonomous_transaction;
v_val number;
begin
update t set rn = rn + 1;
select max(rn) into v_val from t;
dbms_lock.sleep(1); --add this line
commit;
return v_val;
end;
And test in two sessions.
You will NOT get sequential ascending.
>
Think about the effect of two parallel sessionsboth
running this query at the same time, and ask isthis
sensible?Gawd, no, of course not. Like I said, I'd never use
this sort of thing myself. I'm just wondering what
on earth the OP is trying to achieve.
:)Glad to hear it.