Can we rollback the update query using Transaction?

Question

Can we rollback the Update query by writing the update query with in the transaction, as i am implementing different update queries, sometimes I am mistakenly updating the table without where criteria, which is messing up the table. Is there anyway where
we can write the update query within a transaction and rollback that particular update query which I am writing. I do have a backup table, but that wont be useful because we are doing lot of updates in a span of minutes. I researches about Apex Sql logs too,
but we do not have access to download such tools. So, can anyone give me a good solution for this?

Answer 1

Sure, if you use transaction like this
begin transaction
update 1
update 2
rollback transaction
both updates will be rollbacked.
If you want to always be sure about rows you're about to change, always first try with SELECT statement and put each individual UPDATE into separate transaction with rollback at the end, e.g.
begin transaction
   select ... where some condition
   update . where same condition
   select ... where same condition to verify update
rollback transaction
If your last select showed correct info, change ROLLBACK into COMMIT and re-run that script again to perform the actual update.
For every expert, there is an equal and opposite expert. - Becker's Law
My blog
My TechNet articles