PHP | rollback() Function

Hello folks! welcome back to a new edition of our tutorial on PHP. In this tutorial guide, we are going to be studying about the PHP mysqli_rollback() Function.

The PHP mysqli_rollback() function rolls the current transaction to the last save point or the specified save point.

Syntax

Following below is the syntax to use this function -

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

READ: PHP | mysqli_real_connect() Function

Parameter Details

Sr.No	Parameter & Description
1	con(Mandatory) This is an object representing a connection to MySQL Server.
2	flags(Optional) A constant which can be on of the following : MYSQLI_TRANS_COR_AND_CHAIN MYSQLI_TRANS_COR_AND_NO_CHAIN MYSQLI_TRANS_COR_RELEASE MYSQLI_TRANS_COR_NO_RELEASE
3	name(Optional) This is a name value which when given, executes as ROLLBACK/*name*/ .

Return Value

This built-in PHP function returns true if the operation is successful otherwise, false on failure.

PHP Version

This PHP function was first introduced in PHP version 5 and works in all the later versions.

Example1

The following example shows the usage of the built-in mysqli_rollback() function (in a procedural style) -

<?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($con, "insert into my_team values(1, 'Kennedy', 'Nkpara', 'PortHarcourt', 'Nigeria')");
   mysqli_query($con, "insert into my_team values(2, 'Jonathan', 'Trott', 'CapeTown', 'SouthAfrica')");
   mysqli_query($con, "insert into my_team values(3, 'Queen', 'Dauglas', 'Texas', 'UnitedStates')");
   mysqli_query($con, "insert into my_team values(4, 'Paul', 'Francis', 'Texas', 'UnitedStates')");

   $res = mysqli_query($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);
?>

Output

When the above code is executed, it will produce the following result -

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

Example2

In object oriented style the syntax of this built-in PHP function is $con->rollback(); Following is the example of this function in an object oriented style $minus;

//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('Kennedy', 'Nkpara', 'Nigeria')");
$con->query("insert into players values('Jonathan', 'Trott', 'SouthAfrica')");

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

$con->query( "insert into players values('Queen', 'Dauglas', 'UnitedStates')");
$con->query( "insert into players values('Bethel', 'Igwela', 'Nigeria')");

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

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


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

Output

When the above code is executed, it will produce the following result -

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

Example3

Try the following example below -

<?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 ('Precious', 25)");

   mysqli_commit($connection);
   
   mysqli_query($connection, "INSERT INTO test VALUES ('Stephanie', 24)");
   
   mysqli_rollback($connection);
   mysqli_close($connection);
?>

Output

When the above code is executed, if you verify the contents of the table test, you can see the inserted records as shown below -

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

READ: PHP | mysqli_refresh() Function

Alright guys! This is where we are going to be rounding up for this tutorial post. In our next tutorial, we are going to be discussing about the mysqli_select_db() Function in PHP.

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