(PHP 5, PHP 7, PHP 8)
mysqli::change_user -- mysqli_change_user — Changes the user of the specified database connection
面向对象风格
$username, #[\SensitiveParameter] string $password, ?string $database): bool过程化风格
$mysql,$username,$password,$databaseChanges 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.
mysql仅以过程化样式：由 mysqli_connect() 或 mysqli_init() 返回的 mysqli 对象。
usernameThe MySQL user name.
passwordThe MySQL password.
databaseThe 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.
If mysqli error reporting is enabled (MYSQLI_REPORT_ERROR) and the requested operation fails,
a warning is generated. If, in addition, the mode is set to MYSQLI_REPORT_STRICT,
a mysqli_sql_exception is thrown instead.
示例 #1 mysqli::change_user() example
面向对象风格
<?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();
?>过程化风格
<?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);
?>以上示例会输出：
Default database: world Value of variable a is NULL
注意:
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.