(PHP 5, PHP 7, PHP 8)
mysqli::change_user -- mysqli_change_user — Changes the user of the database connection
面向对象风格
$username, #[\SensitiveParameter] string $password, ?string $database): bool过程化风格
$mysql,$username,$password,$databaseAttempts 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 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.
database
The database name. If null or an empty string is passed,
the connection to the server will be opened with no default database.
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 Resetting the connection session
面向对象风格
<?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");
}过程化风格
<?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");
}以上示例会输出：
Default database: world Value of variable a is NULL
示例 #2 If database is null the connection is opened without selecting any default database
面向对象风格
<?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]);以上示例会输出：
Default database:
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.