Cursor for updating table in sql oracle
FOR UPDATE; begin for x in c1 loop some procedural code to look at X if ( some condition based on X ) then delete where current of c1; end if; end loop; end; you really do need the select for update to ensure that no one else updates your data. Now - either sessions would give the following result SQL select empno, ename, job from emp where empno=7369; EMPNO ENAME JOB ---------- ---------- --------- 7369 SMITH2 CLERK Isn't this a case of lost update ?Select for update is a programming tool -- use it when you need to. (not every transcation was using a for update nowait) April 09, 2003 - am UTC yes it is -- your application code is incorrect.
The first value is assigned to the first column in the list, the second value is assigned to the second column in the list, and so on. Only rows that meet the search condition are updated.It also does this to ensure that when the time comes, the delete will proceed in a non-blocking fashion. If we first do a Select for Update, we might have another record coming in when we group by subsequently. Regards, ed Wrote file 1 declare 2 cursor c is 3 select * from equipment_category_lookup for update nowait ; 4 i number; 5 begin 6 for c1 in c loop 7 update equipment_category_lookup 8 set equipment_category_lookup_seq = main_seq.nextval 9 where current of c; 10 end loop; 11* end; SQL / where current of c; * ERROR at line 9: ORA-06550: line 9, column 18: PLS-00404: cursor 'C' must be declared with FOR UPDATE to use with CURRENT OF ORA-06550: line 7, column 1: PL/SQL: SQL Statement ignored SQL ed Wrote file 1 declare 2 cursor c is 3 select * from equipment_category_lookup for update ; 4 i number; 5 begin 6 for c1 in c loop 7 update equipment_category_lookup 8 set equipment_category_lookup_seq = main_seq.nextval 9 where current of c; 10 end loop; 11* end; SQL declare 2 cursor c is 3 select * from emp for update of sal nowait ; 4 i number; 5 begin 6 for c1 in c loop 7 update emp 8 set sal = main_seq.nextval 9 where current of c; 10 end loop; 11 end; 12 / PL/SQL procedure successfully completed.The select for update forms puts on the row ensures o the row was not changed o the row will NOT be changed o the row is locked by you and you will be able to delete it. For Update and Group By cannot be used simultaneously. Tom, Just want to confirm the following : I have 4 identical (same code) processes running.SET column_name = (subquery3) Assigns the value retrieved from the database by list.
The subquery must return exactly one row that includes all the columns listed.It wants to make sure that in the time between T1 and T2 -- no one UPDATED that row. Dear Tom, Please consider this requirement: Field_Code Value Picked_up 10 10 No 20 15 No 10 20 No All the records with "Picked_up=No" are to be selected and populated into another table with "group by" on Field_Code, i.e.