Question

I want to select some rows and immediately update a process column in that row as ‘Y’ before another thread comes and picks it up.

How to do this in Oracle

Initially I had a select for update query which isnt working. what are the ways to achieve this in multi threading mode.

I am using Oracle and couldnt find answers related to oracle in this forum?

Please help

Answer 1

Here’s a simple way of doing it:

Create a table called test:

create table test (id number, col_to_update varchar2(20));

Insert data into table test:

insert into test values (1, 'BOB');
insert into test values (2, 'PETER');
insert into test values (3, 'BOB');
insert into test values (4, 'PETER');
insert into test values (5, 'BOB');

Run PL/SQL block:

declare
  cursor c1 is
   select id
        , col_to_update
          from test
         where col_to_update = 'BOB'
    for update of col_to_update;
begin
   for c1_rec in c1 loop
       update test
              set col_to_update = 'UPDATED'
            where current of c1;
       commit;
   end loop;
end;
/

Result:

You should see all rows with col_to_update ‘BOB’ being updated to ‘UPDATE’;