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PHP mysqli: change_user() Function

mysqli_change_user() function / mysqli::change_user

The mysqli_change_user() function / mysqli::change_user changes the user of the specified database connection, and sets the current database.

Syntax:

Object oriented style

bool mysqli::change_user ( string $user , string $password , string $database )

Procedural style

bool mysqli_change_user ( mysqli $link , string $user , string $password , string $database )

Usage: Procedural style

mysqli_change_user(connection,username,password,dbname);

Parameter:

Name Description Required/Optional
connection Specifies the MySQL connection to use. Required
username Specifies the MySQL username Required
password Specifies the MySQL password Required
dbname Specifies the database to change to Required

Return value:

Returns TRUE on success or FALSE on failure.

Version: PHP 5, PHP 7

Example of object oriented style:

<?php
/* connect database test */
$mysqli = new mysqli("localhost", "user1", "datasoft123", "hr");


/* check connection */
if (mysqli_connect_errno()) {
    printf("Connect failed: %s\n", mysqli_connect_error());
    exit();
}

/* Set Variable a */
$mysqli->query("SET @a:=1");

/* reset all and select a new database */
$mysqli->change_user("my_user", "my_password", "world");

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

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

/* close connection */
$mysqli->close();
?>

Output:

Default database: hr Value of variable a is NULL

Example of procedural style:

<?php
/* connect database test */
$link = mysqli_connect("localhost", "user1", "datasoft123", "hr");

/* check connection */
if (!$link) {
    printf("Connect failed: %s\n", mysqli_connect_error());
    exit();
}

/* Set Variable a */
mysqli_query($link, "SET @a:=1");

/* reset all and select a new database */
mysqli_change_user($link, "user1", "datasoft123", "hr");

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

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

/* close connection */
mysqli_close($link);
?>

Output:

Default database: hr Value of variable a is NULL

See also

PHP Function Reference

Previous: begin_transaction
Next: character_set_name



PHP: Tips of the Day

var_export(): var_export() dumps a PHP parseable representation of the item.

You can pass true as the second parameter to return the contents into a variable.

Example:

<?php
$myarray = [ "PHP", "Tips" ];
$mystring = "PHP Tips";
$myint = 28;

var_export($myarray);
var_export($mystring);
var_export($myint);
?>

Output:

array (
  0 => 'PHP',
  1 => 'Tips',
)'PHP Tips'28

To put the content into a variable, you can do this:

$array_export = var_export($myarray, true);
$string_export = var_export($mystring, true);
$int_export = var_export($myint, 1); // any `Truthy` value

After that, you can output it like this:

printf('$myarray = %s; %s', $array_export, PHP_EOL);
printf('$mystring = %s; %s', $string_export, PHP_EOL);
printf('$myint = %s; %s', $int_export, PHP_EOL);

Example:

<?php
$myarray = [ "PHP", "Tips" ];
$mystring = "PHP Tips";
$myint = 28;
$array_export = var_export($myarray, true);
$string_export = var_export($mystring, true);
$int_export = var_export($myint, 1);
printf('$myarray = %s; %s', $array_export, PHP_EOL);
printf('$mystring = %s; %s', $string_export, PHP_EOL);
printf('$myint = %s; %s', $int_export, PHP_EOL);
?>

This will produce the following output:

Output:

$myarray = array (
  0 => 'PHP',
  1 => 'Tips',
);
$mystring = 'PHP Tips';
$myint = 28;