Open a new connection to the MySQL server_脚本学堂

说明

Object oriented style (constructor):

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") ]]]]]] )

Procedural style

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.

参数

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.

Note: 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.

返回值

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

更新日志

版本	说明
5.3.0	Added the ability of persistent connections.

范例

Example #1 Object oriented style


<?php
$mysqli = new mysqli("localhost", "my_user", "my_password", "world");

/* check connection */
if ($mysqli->connect_error) {
    printf("Connect failed: %s\n", mysqli_connect_error());
    exit();
}

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

/* close connection */
$mysqli->close();
?>

Example #2 Procedural style


<?php
$link = mysqli_connect("localhost", "my_user", "my_password", "world");

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

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

/* close connection */
mysqli_close($link);
?>

上例将输出：

Host information: Localhost via UNIX socket

注释

Note: OO syntax only: If a connection fails an object is still returned. To check if the connection failed then use the mysqli->connect_error property like in the examples above.

Note: 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.