PHP mysqli_connect() Function
The PHP mysqli::__construct() / mysqli::connect() / mysqli_connect() function is used to open a new connection to the MySQL server.
Syntax
//Object-oriented style public mysqli::__construct(hostname, username, password, database, port, socket) public mysqli::connect(hostname, username, password, database, port, socket) //Procedural style mysqli_connect(hostname, username, password, database, port, socket)
Parameters
hostname |
Optional. Specify the host name or an IP address. Passing the null value or "localhost" to this parameter, the local host is assumed. |
username |
Optional. Specify the MySQL user name. |
password |
Optional. Specify the MySQL password. This allows the username to be used with different permissions (depending on if a password is provided or not). |
database |
Optional. If provided will specify the default database to be used when performing queries. |
port |
Optional. Specify the port number to attempt to connect to the MySQL server. |
socket |
Optional. Specify the socket or named pipe that should be used. |
Return Value
Returns as follows:
- 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, or false on failure.
- mysqli::connect() returns null on success or false on failure.
Exceptions
If MYSQLI_REPORT_STRICT is enabled and the attempt to connect to the requested database fails, a mysqli_sql_exception is thrown.
Example: Object-oriented style
The example below shows the usage of mysqli::__construct() method.
<?php //enabling error reporting for mysqli //before attempting to make a connection mysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT); //establishing connection to the database $mysqli = new mysqli("localhost", "user", "password", "database"); printf("Success... %s\n", $mysqli->host_info); ?>
The output of the above code will be similar to:
Success... localhost via TCP/IP
Example: Procedural style
The example below shows the usage of mysqli_connect() function.
<?php //enabling error reporting for mysqli //before attempting to make a connection mysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT); //establishing connection to the database $mysqli = mysqli_connect("localhost", "user", "password", "database"); printf("Success... %s\n", mysqli_get_host_info($mysqli)); ?>
The output of the above code will be similar to:
Success... localhost via TCP/IP
Example: Object-oriented style - manual error handling
If error reporting is disabled, the user is responsible for checking and handling failures. Consider the example below:
<?php error_reporting(0); mysqli_report(MYSQLI_REPORT_OFF); //establishing connection to the database $mysqli = new mysqli("localhost", "user", "password", "database"); if ($mysqli->connect_errno) { throw new RuntimeException('mysqli connection error: ' . $mysqli->connect_error); } if ($mysqli->errno) { throw new RuntimeException('mysqli error: ' . $mysqli->error); } ?>
Example: Procedural style - manual error handling
Consider the example below where error is handled manually in procedural style.
<?php error_reporting(0); mysqli_report(MYSQLI_REPORT_OFF); //establishing connection to the database $mysqli = mysqli_connect("localhost", "user", "password", "database"); if (mysqli_connect_errno()) { throw new RuntimeException('mysqli connection error: ' . mysqli_connect_error()); } if (mysqli_errno($mysqli)) { throw new RuntimeException('mysqli error: ' . mysqli_error($mysqli)); } ?>
❮ PHP MySQLi Reference