Remember that MyISAM tables do not support rollbacks.
I just drove myself crazy for an afternoon trying to figure out what was wrong with my code - meanwhile it was fine all along
(PHP 5, PHP 7)
mysqli::rollback -- mysqli_rollback — 回退当前事务
成功时返回 TRUE， 或者在失败时返回 FALSE。
Example #1 mysqli::rollback() example
面向对象风格
<?php
$mysqli = new mysqli("localhost", "my_user", "my_password", "world");
/* check connection */
if (mysqli_connect_errno()) {
printf("Connect failed: %s\n", mysqli_connect_error());
exit();
}
/* disable autocommit */
$mysqli->autocommit(FALSE);
$mysqli->query("CREATE TABLE myCity LIKE City");
$mysqli->query("ALTER TABLE myCity Type=InnoDB");
$mysqli->query("INSERT INTO myCity SELECT * FROM City LIMIT 50");
/* commit insert */
$mysqli->commit();
/* delete all rows */
$mysqli->query("DELETE FROM myCity");
if ($result = $mysqli->query("SELECT COUNT(*) FROM myCity")) {
$row = $result->fetch_row();
printf("%d rows in table myCity.\n", $row[0]);
/* Free result */
$result->close();
}
/* Rollback */
$mysqli->rollback();
if ($result = $mysqli->query("SELECT COUNT(*) FROM myCity")) {
$row = $result->fetch_row();
printf("%d rows in table myCity (after rollback).\n", $row[0]);
/* Free result */
$result->close();
}
/* Drop table myCity */
$mysqli->query("DROP TABLE myCity");
$mysqli->close();
?>
过程化风格
<?php
$link = mysqli_connect("localhost", "my_user", "my_password", "world");
/* check connection */
if (mysqli_connect_errno()) {
printf("Connect failed: %s\n", mysqli_connect_error());
exit();
}
/* disable autocommit */
mysqli_autocommit($link, FALSE);
mysqli_query($link, "CREATE TABLE myCity LIKE City");
mysqli_query($link, "ALTER TABLE myCity Type=InnoDB");
mysqli_query($link, "INSERT INTO myCity SELECT * FROM City LIMIT 50");
/* commit insert */
mysqli_commit($link);
/* delete all rows */
mysqli_query($link, "DELETE FROM myCity");
if ($result = mysqli_query($link, "SELECT COUNT(*) FROM myCity")) {
$row = mysqli_fetch_row($result);
printf("%d rows in table myCity.\n", $row[0]);
/* Free result */
mysqli_free_result($result);
}
/* Rollback */
mysqli_rollback($link);
if ($result = mysqli_query($link, "SELECT COUNT(*) FROM myCity")) {
$row = mysqli_fetch_row($result);
printf("%d rows in table myCity (after rollback).\n", $row[0]);
/* Free result */
mysqli_free_result($result);
}
/* Drop table myCity */
mysqli_query($link, "DROP TABLE myCity");
mysqli_close($link);
?>
以上例程会输出：
0 rows in table myCity. 50 rows in table myCity (after rollback).
Remember that MyISAM tables do not support rollbacks.
I just drove myself crazy for an afternoon trying to figure out what was wrong with my code - meanwhile it was fine all along
Just a note about auto incremental ids and rollback.
When using transactions and inserting into a table containing a column with auto incremental ids, the id will be incremented even though the transaction is rolled back.
This might occupy a lot of ids if a lot of rollbacks are performed.
Example:
<?php
$mysqli = new mysqli("localhost", "gugbageri", "gugbageri", "gugbageri");
/* check connection */
if (mysqli_connect_errno()) {
printf("Connect failed: %s\n", mysqli_connect_error());
exit();
}
/* disable autocommit */
$mysqli->autocommit(FALSE);
/* We just create a test table with one auto incremental primary column and a content column*/
$mysqli->query("CREATE TABLE TestTable ( `id_column` INT NOT NULL AUTO_INCREMENT , `content` INT NOT NULL , PRIMARY KEY ( `id_column` )) ENGINE = InnoDB;");
/* commit newly created table */
$mysqli->commit();
/* we insert a row */
$mysqli->query("INSERT INTO TestTable (content) VALUES (99)");
/* we commit the inserted row */
$mysqli->commit();
/* we insert another three rows */
$mysqli->query("INSERT INTO TestTable (content) VALUES (99)");
$mysqli->query("INSERT INTO TestTable (content) VALUES (99)");
$mysqli->query("INSERT INTO TestTable (content) VALUES (99)");
/* we the rollback */
$mysqli->rollback();
/* we insert a row */
$mysqli->query("INSERT INTO TestTable (content) VALUES (99)");
/* we commit the inserted row */
$mysqli->commit();
if ($result = $mysqli->query("SELECT id_column FROM TestTable")) {
while($row = $result->fetch_row()) {
printf("Id: %d.\n", $row[0]);
}
/* Free result */
$result->close();
}
/* Drop table TestTable */
$mysqli->query("DROP TABLE TestTable");
$mysqli->close();
?>
This will output:
Id: 1.
Id: 5.
Something to consider when using transact is that you should not perform a normal query on the same table (such as a DELETE) immediately after a transaction. If the transaction rolls-back, the DELETE will execute and even show affected rows, but the row can be magically re-inserted even if the rollback() command comes before the DELETE query.
This is an example to explain the powerful of the rollback and commit functions.
Let's suppose you want to be sure that all queries have to be executed without errors before writing data on the database.
Here's the code:
<?php
$all_query_ok=true; // our control variable
//we make 4 inserts, the last one generates an error
//if at least one query returns an error we change our control variable
$mysqli->query("INSERT INTO myCity (id) VALUES (100)") ? null : $all_query_ok=false;
$mysqli->query("INSERT INTO myCity (id) VALUES (200)") ? null : $all_query_ok=false;
$mysqli->query("INSERT INTO myCity (id) VALUES (300)") ? null : $all_query_ok=false;
$mysqli->query("INSERT INTO myCity (id) VALUES (100)") ? null : $all_query_ok=false; //duplicated PRIMARY KEY VALUE
//now let's test our control variable
$all_query_ok ? $mysqli->commit() : $mysqli->rollback();
$mysqli->close();
?>
hope to be helpful!