(PHP 5)
mysqli::change_user -- mysqli_change_user — Changes the user of the specified database connection
Object oriented style (method):
Procedural style:
Changes the user of the specified database connection and sets the current database.
In order to successfully change users a valid username and password parameters 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.
Procedural style only: A link identifier returned by mysqli_connect() or mysqli_init()
The MySQL user name.
The MySQL password.
The database to change to.
If desired, the NULL value may be passed resulting in only changing the user and not selecting a database. To select a database in this case use the mysqli_select_db() function.
如果成功则返回 TRUE，失败则返回 FALSE。
Note: Using this command will always cause the current database connection to behave as if 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.
Example #1 Object oriented style
<?php
/* connect database test */
$mysqli = new mysqli("localhost", "my_user", "my_password", "test");
/* 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();
?>
Example #2 Procedural style
<?php
/* connect database test */
$link = mysqli_connect("localhost", "my_user", "my_password", "test");
/* check connection */
if (!$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, "my_user", "my_password", "world");
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);
?>
上例将输出：
Default database: world Value of variable a is NULL