mysqli::debug

[edit] Last updated: Fri, 23 Mar 2012

mysqli::__construct

mysqli_connect

(PHP 5)

mysqli::__construct -- mysqli_connect — Open a new connection to the MySQL server

Opis

Styl obiektowy

mysqli::__construct() ([ string $host = ini_get("mysqli.default_host") [, string $username = ini_get("mysqli.default_user") [, string $passwd = ini_get("mysqli.default_pw") [, string $dbname = "" [, int $port = ini_get("mysqli.default_port") [, string $socket = ini_get("mysqli.default_socket") ]]]]]] )

Styl proceduralny

mysqli mysqli_connect ([ string $host = ini_get("mysqli.default_host") [, string $username = ini_get("mysqli.default_user") [, string $passwd = ini_get("mysqli.default_pw") [, string $dbname = "" [, int $port = ini_get("mysqli.default_port") [, string $socket = ini_get("mysqli.default_socket") ]]]]]] )

Opens a connection to the MySQL Server running on.

Parametry

host

Can be either a host name or an IP address. Passing the NULL value or the string "localhost" to this parameter, the local host is assumed. When possible, pipes will be used instead of the TCP/IP protocol.

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.

passwd

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 as provided or not).

dbname

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.

Informacja:
Specifying the socket parameter 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 the host parameter.

Zwracane wartości

Returns an object which represents the connection to a MySQL Server.

Rejestr zmian

Wersja	Opis
5.3.0	Added the ability of persistent connections.

Przykłady

Przykład #1 mysqli::__construct() example

Styl obiektowy


<?php
$mysqli = new mysqli('localhost', 'my_user', 'my_password', 'my_db');

/*
 * This is the "official" OO way to do it,
 * BUT $connect_error was broken until PHP 5.2.9 and 5.3.0.
 */
if ($mysqli->connect_error) {
    die('Connect Error (' . $mysqli->connect_errno . ') '
            . $mysqli->connect_error);
}

/*
 * Use this instead of $connect_error if you need to ensure
 * compatibility with PHP versions prior to 5.2.9 and 5.3.0.
 */
if (mysqli_connect_error()) {
    die('Connect Error (' . mysqli_connect_errno() . ') '
            . mysqli_connect_error());
}

echo 'Success... ' . $mysqli->host_info . "\n";

$mysqli->close();
?>

Styl obiektowy when extending mysqli class


<?php

class foo_mysqli extends mysqli {
    public function __construct($host, $user, $pass, $db) {
        parent::__construct($host, $user, $pass, $db);

        if (mysqli_connect_error()) {
            die('Connect Error (' . mysqli_connect_errno() . ') '
                    . mysqli_connect_error());
        }
    }
}

$db = new foo_mysqli('localhost', 'my_user', 'my_password', 'my_db');

echo 'Success... ' . $db->host_info . "\n";

$db->close();
?>

Styl proceduralny


<?php
$link = mysqli_connect('localhost', 'my_user', 'my_password', 'my_db');

if (!$link) {
    die('Connect Error (' . mysqli_connect_errno() . ') '
            . mysqli_connect_error());
}

echo 'Success... ' . mysqli_get_host_info($link) . "\n";

mysqli_close($link);
?>

Powyższe przykłady wyświetlą:

Success... MySQL host info: localhost via TCP/IP

Notatki

Informacja:
MySQLnd zawsze przyjmuje domyślne kodowanie znaków serwera. To kodowanie jest przesyłane podczas połączenia hand-shake/authentication, którego używa mysqlnd.
Libmysql używa domyślnego kodowania znaków ustawionego w pliku my.cnf lub przez jawne wywołanie funkcji mysqli_options() przed wywołaniem mysqli_real_connect(), ale po wywołaniu mysqli_init().

Informacja:
OO syntax only: If a connection fails an object is still returned. To check if the connection failed then use either the mysqli_connect_error() function or the mysqli->connect_error property as in the preceding examples.

Informacja:
If it is necessary to set options, such as the connection timeout, mysqli_real_connect() must be used instead.

Informacja:
Calling the constructor with no parameters is the same as calling mysqli_init().

Informacja:
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 the SYSTEMROOT environment variable won't be available and PHP will have problems loading Winsock.

Zobacz też:

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 string description of the last connect error
mysqli_close() - Closes a previously opened database connection

mysqli::debug

mysqli::$connect_error

[edit] Last updated: Fri, 23 Mar 2012

add a note User Contributed Notes mysqli::__construct

boukeversteegh at gmail dot com 18-Apr-2011 12:19


(php 5.3.3)



If $port is a string, such as "3306", mysqli::query() will not work, even though mysqli_connect_errno() reports no error (value 0)!



<?php

$mysqli = new mysqli("localhost", "user","password","database", "3306"); //port is a string!

$mysqli->query("SELECT 1;")->fetch_assoc();

// Fatal error: Call to a member function fetch_assoc() on a non-object

?>



This is particularly strange, since mysqli::query() should return a result object, or a boolean.



So, be careful when you read your port from a string or config file. Cast it to int first:

<?php

$port = (int)$port;

?>

Anonymous 13-Sep-2009 11:37


If you get an error like 


  Can't connect to MySQL server on 'localhost' (10061)


and you use named pipes/socket connections (or aren't sure how you installed the MySQL server) try the following connect command:





<?php


mysqli_connect('.', $user_name, $password, $database_name, null, 'mysql');


?>





The '.' as hostname is absolutely necessary when using named pipes. 'localhost' won't work. 'mysql' is the standard name for the pipe/socket.

Slavyansk2.ru 25-Sep-2008 04:14


If you have error like "Trying to clone an uncloneable object of class..." when trying connect, add record 



php_value zend.ze1_compatibility_mode 0



in your .htaccess file. This resolve connection problem.

chip1977 at mail dot ru 27-Jan-2008 09:52


To specify charset in my.cnf file you just have to add 

skip-character-set-client-handshake directive after 

[mysqld]

default-character-set=utf8

add a note