PHP mysqli_rollback()用法及代码示例

定义和用法

MySQL 数据库有一个名为 auto-commit 的函数，如果打开它，数据库中所做的更改会自动保存，如果关闭，则需要使用 mysqli_commit() 函数显式保存更改。

这个mysqli_rollback()函数将当前事务滚动到最后一个保存点(或指定的保存点)。

用法

mysqli_rollback($con, [$flags, $name]);

参数

Sr.No	参数及说明
1	con(Mandatory) 这是一个表示与 MySQL 服务器的连接的对象。
2	flags(Optional) 一个常数，可以是以下之一： MYSQLI_TRANS_COR_AND_CHAIN MYSQLI_TRANS_COR_AND_NO_CHAIN MYSQLI_TRANS_COR_RELEASE MYSQLI_TRANS_COR_NO_RELEASE
3	name(Optional) 这是一个名称值，当给出时，作为 ROLLBACK/*name*/执行。

返回值

PHP mysqli_rollback() 函数返回一个布尔值，如果操作成功则为真，否则为假。

PHP版本

这个函数最初是在 PHP 版本 5 中引入的，并且适用于所有后续版本。

示例

以下示例演示了 mysqli_rollback() 函数的用法(程序风格) -

<?php
   //Creating a connection
   $con = mysqli_connect("localhost", "root", "password", "mydb");

   //Setting auto commit to false
   mysqli_autocommit($con, False);
   mysqli_query($con, "CREATE TABLE IF NOT EXISTS my_team(ID INT, First_Name VARCHAR(255), Last_Name VARCHAR(255), Place_Of_Birth VARCHAR(255), Country VARCHAR(255))");
   //Inserting a records into the my_team table
   mysqli_query($con, "insert into my_team values(1, 'Shikhar', 'Dhawan', 'Delhi', 'India')");
   mysqli_query($con, "insert into my_team values(2, 'Jonathan', 'Trott', 'CapeTown', 'SouthAfrica')");
   mysqli_query($con, "insert into my_team values(3, 'Kumara', 'Sangakkara', 'Matale', 'Srilanka')");
   mysqli_query($con, "insert into my_team values(4, 'Virat', 'Kohli', 'Delhi', 'India')");

   $res = mysqli_query($con, "SELECT * FROM my_team");
   print("No.of rows (at the time of commit):".mysqli_affected_rows($con)."\n");

   //Saving the changes
   mysqli_commit($con);

   //Truncating the table
   mysqli_query($con, "DELETE FROM my_team where id in(3,4)"); 
   $res = mysqli_query($con, "SELECT * FROM my_team");
   print("No.of rows (before roll back):".mysqli_affected_rows($con)."\n");

   //Roll back
   mysqli_rollback($con);

   //Contents of the table
   $res = mysqli_query($con, "SELECT * FROM my_team");
   print("No.of rows (after roll back):".mysqli_affected_rows($con));

   //Closing the connection
   mysqli_close($con);
?>

这将产生以下结果 -

No.of rows (at the time of commit):4
No.of rows (before roll back):2
No.of rows (after roll back):4

示例

这种面向对象风格的方法的语法是 $con->rollback()。以下是面向对象模式 $minus 中此函数的示例；

//Creating a connection
$con = new mysqli("localhost", "root", "password", "mydb");

//Setting auto commit to false
$con->autocommit(FALSE);

//Inserting a records into the players table
$con->query("CREATE TABLE IF NOT EXISTS players(First_Name VARCHAR(255), Last_Name VARCHAR(255), Country VARCHAR(255))");
$con->query("insert into players values('Shikhar', 'Dhawan', 'India')");
$con->query("insert into players values('Jonathan', 'Trott', 'SouthAfrica')");

//Saving the results
$con->commit();

$con->query( "insert into players values('Kumara', 'Sangakkara', 'Srilanka')");
$con->query( "insert into players values('Virat', 'Kohli', 'India')");

//Roll back
$con->rollback();

$res = $con->query("SELECT * FROM players");
print_r($res);


//Closing the connection
$res = $con -> close();
?>

这将产生以下结果 -

mysqli_result Object
(
    [current_field] => 0
    [field_count] => 3
    [lengths] =>
    [num_rows] => 2
    [type] => 0
)

示例

<?php
   $connection = mysqli_connect("localhost", "root", "password", "mydb");
   
   if (mysqli_connect_errno($connection)){
      echo "Failed to connect to MySQL:" . mysqli_connect_error();
   }
   mysqli_autocommit($connection,FALSE); 
   
   mysqli_query($connection, "create table test(Name VARCHAR(255), Age INT)");   
   mysqli_query($connection, "INSERT INTO test VALUES ('Sharukh', 25)");

   mysqli_commit($connection);
   
   mysqli_query($connection, "INSERT INTO test VALUES ('Kalyan', 30)");
   
   mysqli_rollback($connection);
   mysqli_close($connection);
?>

执行上述程序后，如果您验证表测试的内容，您可以看到插入的记录为 -

mysql> select * from test;
+---------+------+
| Name    | Age  |
+---------+------+
| Sharukh |   25 |
+---------+------+
1 row in set (0.00 sec)