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Sometimes errors happen in the middle of a transaction. How do you recover from that? This video shows you how!
SQL Used
To reset the state of the database to before the begining of the transaction:
ROLLBACK;
See all of the SQL used in Modifying Data With SQL in the Modifying Data With SQL Cheatsheet.
Now that you've seen the benefit of using
transactions in database save files,
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you may be tempted to use them on your
own for a series of complex updates.
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Now, what happens in the middle of
a transaction when you make a typo or
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you forget something, and
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you just want to get rid of the changes
that haven't been committed yet?
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This is where the rollback
statement comes in.
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Let's say you begin your transaction and
start inserting rows.
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You can even select to see them added,
but they're not really added.
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No one else can see them
if they run the same query.
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It's just for you to review.
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[SOUND] Then you realize you've done
a typo in all of your statements and
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you feel like starting over.
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That's where rollback comes in.
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To undo it,
we issue the rollback statement.
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When you select from the table now,
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the entries you tried to
insert aren't there anymore.
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That's because they weren't
there in the first place.
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You didn't commit your changes.
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You may have issued multiple
code operations in one go.
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And issuing them by hand
can be problematic.
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But rolling back is always an option.
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