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Modifying Data with SQL

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Rolling Back from Transactions

1:15 with Andrew Chalkley

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 beginning of the transaction:

ROLLBACK;

See all of the SQL used in Modifying Data With SQL in the Modifying Data With SQL Cheatsheet.

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    Now that you've seen the benefit of using transactions in database save files, 0:00
    you may be tempted to use them on your own for a series of complex updates. 0:04
    Now, what happens in the middle of a transaction when you make a typo or 0:09
    you forget something, and 0:13
    you just want to get rid of the changes that haven't been committed yet? 0:14
    This is where the rollback statement comes in. 0:18
    Let's say you begin your transaction and start inserting rows. 0:22
    You can even select to see them added, but they're not really added. 0:27
    No one else can see them if they run the same query. 0:34
    It's just for you to review. 0:38
    [SOUND] Then you realize you've done a typo in all of your statements and 0:40
    you feel like starting over. 0:46
    That's where rollback comes in. 0:48
    To undo it, we issue the rollback statement. 0:52
    When you select from the table now, 0:55
    the entries you tried to insert aren't there anymore. 0:57
    That's because they weren't there in the first place. 1:00
    You didn't commit your changes. 1:03
    You may have issued multiple code operations in one go. 1:06
    And issuing them by hand can be problematic. 1:09
    But rolling back is always an option. 1:12

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