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ALTER TABLE
CREATE INDEX
DROP DATABASE
DROP INDEX
DROP TABLE
LOAD MASTER DATA
LOCK TABLES
RENAME TABLE
TRUNCATE TABLE
UNLOCK TABLES (if tables currently are locked)
If the client connection ends or is broken during a transaction before a commit occurs, the server rolls back the transaction automatically.
Transactions are useful in all kinds of situations. For example, suppose you're working with the score table that is part of the grade-keeping project and you discover that the grades for two students have gotten mixed up and need to be switched. The grades as entered incorrectly are as follows:
mysql> SELECT * FROM score WHERE event_id = 5 AND student_id IN (8,9);
To fix this, student 8 should be given a score of 13 and student 9 a score of 18. That can be done easily with two statements:
UPDATE score SET score = 13 WHERE event_id = 5 AND student_id = 8;
UPDATE score SET score = 18 WHERE event_id = 5 AND student_id = 9;
However, it's necessary to ensure that both statements succeed as a unit—a problem to which transactional methods can be applied. To use BEGIN, do the following:
mysql> BEGIN;
mysql> UPDATE score SET score = 13 WHERE event_id = 5 AND student_id = 8;
mysql> UPDATE score SET score = 18 WHERE event_id = 5 AND student_id = 9;
mysql> COMMIT;
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