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mysqli::change_user

PHP function Edit on GitHub ✎

(PHP 5, PHP 7, PHP 8)

Changes the user of the database connection

Description

Oop

mysqli::change_user(string $username, string $password, string|null $database): bool

Procedural

mysqli_change_user(mysqli $mysql, string $username, string $password, string|null $database): bool

Attempts to connect to the specified database using the provided credentials.

In comparison to mysqli::connect, this method will not disconnect the current connection if the new connection cannot be opened.

In order to successfully change users, a valid username and password must be provided, and that user must have sufficient permissions to access the desired database. If for any reason authorization fails, the current user authentication will remain.

Parameters

username: The MySQL user name.
password: The MySQL password.
database: The database name. If null or an empty string is passed, the connection to the server will be opened with no default database.

Return Values

Success

Errors/Exceptions Conditionalexception

Examples

Resetting the connection session

Oop

php

<?php

mysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT);
$mysqli = new mysqli("localhost", "my_user", "my_password", "test");

$mysqli->query("SET @a:=1");

$mysqli->change_user("my_user", "my_password", "world");

$result = $mysqli->query("SELECT DATABASE()");
$row = $result->fetch_row();
printf("Default database: %s\n", $row[0]);

$result = $mysqli->query("SELECT @a");
$row = $result->fetch_row();
if ($row[0] === null) {
    printf("Value of variable a is NULL\n");
}

Procedural

php

<?php

mysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT);
$link = mysqli_connect("localhost", "my_user", "my_password", "test");

mysqli_query($link, "SET @a:=1");

mysqli_change_user($link, "my_user", "my_password", "world");

$result = mysqli_query($link, "SELECT DATABASE()");
$row = mysqli_fetch_row($result);
printf("Default database: %s\n", $row[0]);

$result = mysqli_query($link, "SELECT @a");
$row = mysqli_fetch_row($result);
if ($row[0] === null) {
    printf("Value of variable a is NULL\n");
}

Outputs

output

Default database: world
Value of variable a is NULL

If database is null the connection is opened without selecting any default database

Oop

php

<?php

mysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT);
$mysqli = new mysqli("localhost", "my_user", "my_password", "test");

$mysqli->change_user("my_user", "my_password", null);

$result = $mysqli->query("SELECT DATABASE()");
$row = $result->fetch_row();
printf("Default database: %s\n", $row[0]);

Outputs

output

Default database:

Notes

Note

Using this command will always cause the current database connection to behave as if it was a completely new database connection, regardless of if the operation was completed successfully. This reset includes performing a rollback on any active transactions, closing all temporary tables, and unlocking all locked tables.