Transaction rollback doesn't work

问题

I have made a database wrapper with extra functionality around the PDO system (yes, i know a wrapper around a wrapper, but it is just PDO with some extra functionality). But i have noticed a problem.

The folowing doesn't work like it should be:

<?php
var_dump($db->beginTransaction());

$db->query('
 INSERT INTO test
 (data) VALUES (?)
 ;',
 array(
  'Foo'
 )
);
print_r($db->query('
 SELECT *
 FROM test
 ;'
)->fetchAll());

var_dump($db->rollBack());

print_r($db->query('
 SELECT *
 FROM test
 ;'
)->fetchAll());
?>

The var_dump's shows that the beginTransaction and rollBack functions return true, so no errors.

I expected that the first print_r call show a array of N items and the second call show N-1 items. But that issn't true, they both show same number of items.

My $db->query(< sql >, < values >) call nothing else then $pdo->prepare(< sql >)->execute(< values >) (with extra error handling ofcourse).

So i think or the transaction system of MySQL doesn't work, or PDO's implenmentaties doesn't work or i see something wrong.

Does anybody know what the problem is?

回答1:

Check if your type of database equals innoDB. In one word you must check if your database supports transactions.

回答2:

Two possible problems:

The table is MyISAM which doesn't support transaction. Use InnoDB.
Check to make sure auto-commit is OFF.

http://www.php.net/manual/en/pdo.transactions.php

回答3:

I'm entering this as an answer, as a comment is to small to contain the following:

PDO is just a wrapper around the various lower level database interface libraries. If the low-level library doesn't complain, either will PDO. Since MySQL supports transactions, no transaction operations will return a syntax error or whatever. You can use MyISAM tables within transactions, but any operations done on them will be done as if auto-commit was still active:

mysql> create table myisamtable (x int) engine=myisam;
Query OK, 0 rows affected (0.00 sec)

mysql> create table innodbtable (x int) engine=innodb;
Query OK, 0 rows affected (0.00 sec)

mysql> start transaction;
Query OK, 0 rows affected (0.00 sec)

mysql> insert into myisamtable (x) values (1);
Query OK, 1 row affected (0.00 sec)

mysql> insert into innodbtable (x) values (2);
Query OK, 1 row affected (0.00 sec)

mysql> rollback;
Query OK, 0 rows affected, 1 warning (0.00 sec)

mysql> select * from myisamtable;
+------+
| x    |
+------+
|    1 |
+------+
1 row in set (0.00 sec)

mysql> select * from innodbtable;
Empty set (0.00 sec)

mysql>

As you can see, even though a transaction was active, and some actions were performed on the MyISAM table, no errors were thrown.

回答4:

MySQL doesn't support transactions on the MyISAM table type, which is unfortunately the default table type.

If you need transactions, you should switch to the InnoDB table type.

回答5:

Another reason this may happen is certain types of SQL statements cause an immediate auto-commit. I had a large script that ran in a transaction that was getting committed immediately and ignored the transaction. I eventually found out it was because any ALTER TABLE statement immediately causes a commit to happen.

Types of statements that cause auto commits are:

Anything that modifies a table or the database, such as ALTER TABLE, CREATE TABLE, etc.
Anything that modifies table permissions, such as ALTER USER or SET PASSWORD
Anything that locks that tables or starts a new transaction
Data loading statements
Administrative statements, such as ANALYZE TABLE, FLUSH, or CACHE INDEX
Replication control statements, such as anything to do with a slave or master

More info and a complete list can be found here: https://dev.mysql.com/doc/refman/8.0/en/implicit-commit.html

If you're having this problem only with a specific script and you're sure you're using InnoDB, you might want to look to see if any SQL statements in your script match these.

来源：https://stackoverflow.com/questions/2281754/transaction-rollback-doesnt-work

标签

php

mysql

pdo

transactions