|I don't think you read my post fully.
Before the update run a query like this:
select * into temp_20140219 from cash_withdrawals where userid = 1234
You then run your update:
update cash_withdrawals set withdrawals = -1000000 where id = 1234
You then check that the update worked correctly:
select * from cash_withdrawals where userid = 1234
If everything looks correct you then drop the backup table.
drop table temp_20140219
If there is a problem you restore the data:
delete from cash_withdrawals where id = 1234
insert into cash_withdrawals
select * from temp_20140219
If you carry on with things the way you currently do you will get burnt, maybe not this weeek but it will happen eventually...
[EDIT]SQL syntax error corrected[/EDIT]
“That which can be asserted without evidence, can be dismissed without evidence.”
― Christopher Hitchens