Open a new connection to the MySQL server (PHP 5)
mysqli mysqli_connect ( [string host [, string username [, string passwd [, string dbname [, int port [, string socket]]]]]] )

Procedural style

Object oriented style (constructor):

mysqli {
  __construct(string host,
              string username,
              string passwd,
              string dbname,
              int port,
              string socket);


The mysqli_connect() function attempts to open a connection to the MySQL Server running on host which 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. If successful, the mysqli_connect() will return an object representing the connection to the database, or FALSE on failure.

The username and password parameters specify the username and password under which to connect to the MySQL server. If the password is not provided (the NULL value is passed), 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).

The dbname parameter if provided will specify the default database to be used when performing queries.

The port and socket parameters are used in conjunction with the host parameter to further control how to connect to the database server. The port parameter specifies the port number to attempt to connect to the MySQL server on, while the socket parameter specifies the socket or named pipe that should be used.


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.


Returns a object which represents the connection to a MySQL Server or FALSE if the connection failed.


例 1258. Object oriented style

= new mysqli("localhost", "my_user", "my_password", "world");

/* check connection */
if (mysqli_connect_errno()) {
printf("Connect failed: %s\n", mysqli_connect_error());

printf("Host information: %s\n", $mysqli->host_info);

/* close connection */

例 1259. Procedural style

= mysqli_connect("localhost", "my_user", "my_password", "world");

/* check connection */
if (!$link) {
printf("Connect failed: %s\n", mysqli_connect_error());

printf("Host information: %s\n", mysqli_get_host_info($link));

/* close connection */


Host information: Localhost via UNIX socket