mysqli_rollback()函數(shù)回退當(dāng)前事務(wù)
MySQL數(shù)據(jù)庫(kù)具有自動(dòng)提交事務(wù)的功能，如果您將其打開，則會(huì)自動(dòng)保存在數(shù)據(jù)庫(kù)中所做的更改；如果將其關(guān)閉，則需要使用mysqli_commit()函數(shù)顯式保存更改。
mysqli_rollback()函數(shù)將當(dāng)前事務(wù)滾動(dòng)到最后一個(gè)保存點(diǎn)（或指定的保存點(diǎn)）。
mysqli_rollback($con, [$flags, $name]);
| 序號(hào) | 參數(shù)及說明 |
|---|---|
| 1 | con(必需) 這是一個(gè)表示與MySQL Server的連接的對(duì)象。 |
| 2 | flags(可選) 可以是下列常量之一：
|
| 3 | name(可選) 這是一個(gè)名稱值，當(dāng)給定時(shí)，將作為 ROLLBACK /* name */ 執(zhí)行。 |
mysqli_rollback()函數(shù)返回一個(gè)布爾值，如果操作成功，則為true，否則為false。
此函數(shù)最初是在PHP版本5中引入的，并且在所有更高版本中均可用。
以下示例演示了mysqli_rollback()函數(shù)的用法（面向過程風(fēng)格）-
<?php
//建立連接
$con = mysqli_connect("localhost", "root", "password", "mydb");
//將自動(dòng)提交設(shè)置為false
mysqli_autocommit($con, False);
mysqli_query($con, "CREATE TABLE IF NOT EXISTS my_team(ID INT, First_Name VARCHAR(255), Last_Name VARCHAR(255), Place_Of_Birth VARCHAR(255), Country VARCHAR(255))");
//將記錄插入到my_team表中
mysqli_query($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("行數(shù)（提交時(shí)）: ".mysqli_affected_rows($con)."\n");
//保存更改
mysqli_commit($con);
//截?cái)啾? mysqli_query($con, "DELETE FROM my_team where id in(3,4)");
$res = mysqli_query($con, "SELECT * FROM my_team");
print("行數(shù)（回滾之前）: ".mysqli_affected_rows($con)."\n");
//回退
mysqli_rollback($con);
//表中的內(nèi)容
$res = mysqli_query($con, "SELECT * FROM my_team");
print("行數(shù)(回滾后): ".mysqli_affected_rows($con));
//關(guān)閉連接
mysqli_close($con);
?>輸出結(jié)果
行數(shù)（提交時(shí)）: 4 行數(shù)（回滾之前）: 2 行數(shù)(回滾后): 4
面向?qū)ο箫L(fēng)格的此方法的語(yǔ)法為$con->rollback()。以下是面向?qū)ο箫L(fēng)格中此函數(shù)的示例；
//建立連接
$con = new mysqli("localhost", "root", "password", "mydb");
//將自動(dòng)提交設(shè)置為false
$con->autocommit(FALSE);
//在players表中插入一個(gè)記錄
$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')");
//保存結(jié)果
$con->commit();
$con->query( "insert into players values('Kumara', 'Sangakkara', 'Srilanka')");
$con->query( "insert into players values('Virat', 'Kohli', 'India')");
//回退
$con->rollback();
$res = $con->query("SELECT * FROM players");
print_r($res);
//關(guān)閉連接
$res = $con -> close();
?>輸出結(jié)果
mysqli_result Object ( [current_field] => 0 [field_count] => 3 [lengths] => [num_rows] => 2 [type] => 0 )
關(guān)閉自動(dòng)提交，做一些查詢，提交查詢，然后回滾當(dāng)前事務(wù)：
<?php
$connection = mysqli_connect("localhost", "root", "password", "mydb");
if (mysqli_connect_errno($connection)){
echo "連接MySQL失敗: " . 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);
?>執(zhí)行以上程序后，如果驗(yàn)證表test的內(nèi)容，則可以看到插入的記錄為-
mysql> select * from test; +---------+------+ | Name | Age | +---------+------+ | Sharukh | 25 | +---------+------+ 1 row in set (0.00 sec)