Beginning Microsoft SQL Server 2008 ... - S3 Tech Training

we are unable or do not want to commit the transaction, this is the point to which all database activity
will be rolled back. That is, everything beyond this point that is not eventually committed will effectively
be forgotten, as far as the database is concerned.
The syntax is:
BEGIN TRAN[SACTION] [|]
[ WITH MARK [ ]]
I won’t dwell on the WITH MARK option here, as it is a topic having to do with very advanced point in
time transaction work, which tends to be more administrator oriented and is well outside of the scope of
this book.
COMMIT TRAN
The committing of a transaction is the end of a completed transaction. At the point that you issue the
COMMIT TRAN, the transaction is considered durable. That is, the effect of the transaction is now permanent
and will last even if you have a system failure (as long as you have a backup or the database files haven’t
been physically destroyed). The only way to undo whatever the transaction accomplished is to issue a
new transaction that, functionally speaking, is a reverse of your first transaction.
The syntax for a COMMIT looks pretty similar to a BEGIN:
COMMIT TRAN[SACTION] [|]
ROLLBACK TRAN
Whenever I think of a ROLLBACK, I think of the old movie The Princess Bride. If you’ve ever seen the film
(if you haven’t, I highly recommend it), you’ll know that the character Vizzini (considered a genius in
the film) always says, “If anything goes wrong, go back to the beginning.”
That is some mighty good advice. A ROLLBACK does just what Vizzini suggests — it goes back to the
beginning. In this case, it’s your transaction that goes back to the beginning. Anything that happened
since the associated BEGIN statement is effectively forgotten. The only exception to going back to the
beginning is through the use of what are called save points, which we’ll describe shortly.
The syntax for a ROLLBACK again looks pretty much the same as a BEGIN or COMMIT, with the exception
of allowance for a save point.
ROLLBACK TRAN[SACTION] [||
|]
SAVE TRAN
Chapter 14: Transactions and Locks
To save a transaction is essentially to create something of a bookmark. You establish a name for your
bookmark (you can have more than one). After this bookmark is established, you can reference it in a
rollback. What’s nice about this is that you can roll back to the exact spot in the code that you want to
just by naming a save point to which you want to roll back.
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