PHP 5.4.36 Released

mysqli::__construct

mysqli_connect

(PHP 5)

mysqli::__construct -- mysqli_connectOpen a new connection to the MySQL server

Descrierea

Stil obiect-orientat

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") ]]]]]] )

Stil procedural

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.

Parametri

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.

Notă:

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.

Valorile întoarse

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

Istoria schimbărilor

Versiunea Descriere
5.3.0 Added the ability of persistent connections.

Exemple

Example #1 mysqli::__construct() example

Stil obiect-orientat

<?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();
?>

Stil obiect-orientat 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();
?>

Stil procedural

<?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);
?>

Exemplele de mai sus vor afișa:

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

Note

Notă:

MySQLnd întotdeauna preia setul de caractere implicit de pe server. Acest set de caractere este transmis în momentul stabilirii parametrilor/autentificării la conectare și este utilizat ulterior de mysqlnd.

Libmysqlclient utilizează setul de caractere implicit stabilit în fișierul my.cnf sau printr-un apel explicit al funcției mysqli_options() înainte de apelul mysqli_real_connect(), dar după mysqli_init().

Notă:

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.

Notă:

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

Notă:

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

Notă:

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.

Vedeți de asemenea

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User Contributed Notes 8 notes

up
17
boukeversteegh at gmail dot com
3 years ago
(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;
?>
up
3
andres at 21brains dot com
6 months ago
Please do use set_charset("utf8") after establishing the connection if you want to avoid weird string issues. I do not know why the documentation does not warn you about this kind of stuff.

We had a hard time figuring out what was going on since we were using mb_detect_encoding and it said everything was UTF-8, but of course the display was wrong. If we used iconv from ISO-8859-1 to UTF-8 the strings looked fine, even though everything in the database had the right collation. So in the end, it was the connection that was the filter and although the notes for this function mention default charsets, it almost reads as a sidenote instead of a central issue when dealing with UTF and PHP/MySQL.
up
4
fugyl13 at gmail dot com
8 months ago
Note that on all >=Windows 7 Servers, a host name "localhost" will create a very expensive lookup (~1 Second).

That's because since Windows 7, the hosts file doesn't come with a preconfigured
127.0.0.1 localhost
anymore

So, if you notice a long connection creation, try "127.0.0.1" instead.
up
2
paul at mtnlist dot com
1 year ago
If you want to connect via an alternate port (other than 3306), as you might when using an ssh tunnel to another host, using "localhost" as the hostname will not work.

Using 127.0.0.1 will work.  Apparently, if you specify the host as "localhost", the constructor ignores the port specified as an argument to the constructor.
up
3
Anonymous
5 years ago
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.
up
1
oleg at mastak dot fi
1 year ago
If you want to connect to local named pipe on windows and you get error "php_network_getaddresses: getaddrinfo failed: No such host is known. ", even if you using using "." as host, please check your if you are using mysqlnd driver: If this is true, then probably you need to update to version 5.4 of php:

Named pipes support for Windows was added in PHP version 5.4.0.
@ http://php.net/manual/en/mysqlnd.overview.php

Hopefully that will save you some time.
up
0
linguafranca2003 at yahoo dot com
24 days ago
mysqli can succeed in surprising ways, depending on the privileges granted to the user. For example,

GRANT USAGE ON *.* TO 'myuser'@'localhost' IDENTIFIED BY PASSWORD 'mypassword';
GRANT ALL PRIVILEGES ON `database_a`.* TO 'myuser'@'localhost';
CREATE DATABASE database_b;

<?php
$db
= new mysqli('localhost', 'myuser', 'mypassword', 'database_b');

if (
$db->connect_error) {
        die(
'Connect Error (' . $db->connect_errno . ') '
           
. $mysqli->connect_error);
}

printf("SQLSTATE: %s\n", $this->db->sqlstate);
printf("Warning Count: %s\n", $db->warning_count);
$db->close();
?>

Will output:

SQLSTATE: 00000
Warning Count: 0

So, life is good — you're connected to the database and executing mysqli methods. Except, life isn't good, because you aren't actually using database_b because myuser doesn't have any privileges on it. You won't catch this until you try to perform a later operation, when you'll get an error, "MYSQL Error: No database selected", and find yourself scratching your head and thinking "what do you mean, of course I have a database selected; I selected one when I called the constructor".

As a result, you may want to perform an additional check after connecting to mysql, to confirm that you're actually connected not just to the mysql server, but to the actual database:

<?php
$db
= new mysqli('localhost', 'myuser', 'mypassword', 'database_b');

if (
$db->connect_error) {
        die(
'Connect Error (' . $db->connect_errno . ') '
           
. $mysqli->connect_error);
} elseif (
$result = $db->query("SELECT DATABASE()")) {
       
$row = $result->fetch_row();
        if (
$row[0] != 'database_b') {
               
//oops! We're connected to mysql, but not to database_b
       
}
}
?>
up
-8
Slavyansk2.ru
6 years ago
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.
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