mysqli::__construct
mysqli::connect
mysqli_connect
(PHP 5, PHP 7, PHP 8)
mysqli::__construct -- mysqli::connect -- mysqli_connect — Open a new connection to the MySQL server
Beschreibung
Objektorientierter Stil
string
$hostname = ini_get("mysqli.default_host"),string
$username = ini_get("mysqli.default_user"),string
$password = ini_get("mysqli.default_pw"),string
$database = "",int
$port = ini_get("mysqli.default_port"),string
$socket = ini_get("mysqli.default_socket"))
string
$hostname = ini_get("mysqli.default_host"),string
$username = ini_get("mysqli.default_user"),string
$password = ini_get("mysqli.default_pw"),string
$database = "",int
$port = ini_get("mysqli.default_port"),string
$socket = ini_get("mysqli.default_socket")): void
Prozeduraler Stil
string
$hostname = ini_get("mysqli.default_host"),string
$username = ini_get("mysqli.default_user"),string
$password = ini_get("mysqli.default_pw"),string
$database = "",int
$port = ini_get("mysqli.default_port"),string
$socket = ini_get("mysqli.default_socket")): mysqli|false
Opens a connection to the MySQL Server.
Parameter-Liste
-
hostname -
Can be either a host name or an IP address. The local host is assumed when passing the
nullvalue or the string "localhost" to this parameter. When possible, pipes will be used instead of the TCP/IP protocol. The TCP/IP protocol is used if a host name and port number are provided together e.g.localhost:3308.Prepending host by
p:opens a persistent connection. mysqli_change_user() is automatically called on connections opened from the connection pool. -
username -
The MySQL user name.
-
password -
If not provided or
null, the MySQL server will attempt to authenticate the user against those user records which have no password only. This allows one username to be used with different permissions (depending on if a password is provided or not). -
database -
If provided will specify the default database to be used when performing queries.
-
port -
Specifies the port number to attempt to connect to the MySQL server.
-
socket -
Specifies the socket or named pipe that should be used.
Hinweis:
Specifying the
socketparameter will not explicitly determine the type of connection to be used when connecting to the MySQL server. How the connection is made to the MySQL database is determined by thehostnameparameter.
Rückgabewerte
mysqli::__construct() always returns an object which represents the connection to a MySQL Server, regardless of it being successful or not.
mysqli_connect() returns an object which represents the connection to a MySQL Server,
Bei einem Fehler wird false zurückgegeben..
mysqli::connect() returns null on successBei einem Fehler wird false zurückgegeben..
Fehler/Exceptions
If MYSQLI_REPORT_STRICT is enabled and the attempt to connect
to the requested database fails, a mysqli_sql_exception is thrown.
Beispiele
Beispiel #1 mysqli::__construct() example
Objektorientierter Stil
<?php
/* You should enable error reporting for mysqli before attempting to make a connection */
mysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT);
$mysqli = new mysqli('localhost', 'my_user', 'my_password', 'my_db');
/* Set the desired charset after establishing a connection */
$mysqli->set_charset('utf8mb4');
printf("Success... %s\n", $mysqli->host_info);
Prozeduraler Stil
<?php
/* You should enable error reporting for mysqli before attempting to make a connection */
mysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT);
$mysqli = mysqli_connect('localhost', 'my_user', 'my_password', 'my_db');
/* Set the desired charset after establishing a connection */
mysqli_set_charset($mysqli, 'utf8mb4');
printf("Success... %s\n", mysqli_get_host_info($mysqli));
Die oben gezeigten Beispiele erzeugen eine ähnliche Ausgabe wie:
Success... localhost via TCP/IP
Beispiel #2 Extending mysqli class
<?php
class FooMysqli extends mysqli {
public function __construct($host, $user, $pass, $db, $port, $socket, $charset) {
mysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT);
parent::__construct($host, $user, $pass, $db, $port, $socket);
$this->set_charset($charset);
}
}
$db = new FooMysqli('localhost', 'my_user', 'my_password', 'my_db', 3306, null, 'utf8mb4');
Beispiel #3 Manual error handling
If error reporting is disabled, the developer is responsible for checking and handling failures
Objektorientierter Stil
<?php
error_reporting(0);
mysqli_report(MYSQLI_REPORT_OFF);
$mysqli = new mysqli('localhost', 'my_user', 'my_password', 'my_db');
if ($mysqli->connect_errno) {
throw new RuntimeException('mysqli connection error: ' . $mysqli->connect_error);
}
/* Set the desired charset after establishing a connection */
$mysqli->set_charset('utf8mb4');
if ($mysqli->errno) {
throw new RuntimeException('mysqli error: ' . $mysqli->error);
}
Prozeduraler Stil
<?php
error_reporting(0);
mysqli_report(MYSQLI_REPORT_OFF);
$mysqli = mysqli_connect('localhost', 'my_user', 'my_password', 'my_db');
if (mysqli_connect_errno()) {
throw new RuntimeException('mysqli connection error: ' . mysqli_connect_error());
}
/* Set the desired charset after establishing a connection */
mysqli_set_charset($mysqli, 'utf8mb4');
if (mysqli_errno($mysqli)) {
throw new RuntimeException('mysqli error: ' . mysqli_error($mysqli));
}
Anmerkungen
Hinweis:
MySQLnd nimmt immer den Standardzeichensatz des Servers an. Dieser Zeichensatz wird während des Aufbaus der Verbindung bzw. der Authentifizierung übermittelt und danach von MySQLnd verwendet.
Libmysqlclient verwendet als Standardzeichensatz den, der in der Datei my.cnf angegeben oder durch einen Aufruf von mysqli_options() vor dem Aufruf von mysqli_real_connect() aber nach mysqli_init() gesetzt wurde.
Hinweis:
Objektorientierter Stil only: If the connection fails, an object is still returned. To check whether the connection failed, use either the mysqli_connect_error() function or the mysqli->connect_error property as in the preceding examples.
Hinweis:
If it is necessary to set options, such as the connection timeout, mysqli_real_connect() must be used instead.
Hinweis:
Calling the constructor with no parameters is the same as calling mysqli_init().
Hinweis:
Error "Can't create TCP/IP socket (10106)" usually means that the variables_order configure directive doesn't contain character
E. On Windows, if the environment is not copied theSYSTEMROOTenvironment variable won't be available and PHP will have problems loading Winsock.
Siehe auch
- mysqli_real_connect() - Opens a connection to a mysql server
- mysqli_options() - Set options
- mysqli_connect_errno() - Returns the error code from last connect call
- mysqli_connect_error() - Returns a description of the last connection error
- mysqli_close() - Schließt die zuvor geöffnete Datenbankverbindung
