MySQL Database Connection

Opening Database Connection

PHP provides mysql_connect function to open a database connection. This function takes five parameters and returns a MySQL link identifier on success, or FALSE on failure.

Syntax

connection mysql_connect(server,user,passwd,new_link,client_flag);

Sr.No	Parameter & Description
1	server Optional − The host name running database server. If not specified then default value is localhost:3306.
2	user Optional − The username accessing the database. If not specified then default is the name of the user that owns the server process.
3	passwd Optional − The password of the user accessing the database. If not specified then default is an empty password.
4	new_link Optional − If a second call is made to mysql_connect() with the same arguments, no new connection will be established; instead, the identifier of the already opened connection will be returned.
5	client_flags Optional − A combination of the following constants − MYSQL_CLIENT_SSL − Use SSL encryption MYSQL_CLIENT_COMPRESS − Use compression protocol MYSQL_CLIENT_IGNORE_SPACE − Allow space after function names MYSQL_CLIENT_INTERACTIVE − Allow interactive timeout seconds of inactivity before closing the connection

NOTE − You can specify server, user, passwd in php.ini file instead of using them again and again in your every PHP scripts. Check php.ini file configuration.

Closing Database Connection

Its simplest function mysql_close PHP provides to close a database connection. This function takes connection resource returned by mysql_connect function. It returns TRUE on success or FALSE on failure.

Syntax

bool mysql_close ( resource $link_identifier );

If a resource is not specified then last opend database is closed.

Example

Try out following example to open and close a database connection −

<?php
   
   $dbhost = 'localhost:3036';
   $dbuser = 'guest';
   $dbpass = 'guest123';
   $conn = mysql_connect($dbhost, $dbuser, $dbpass);
   
   if(! $conn ) {
      die('Could not connect: ' . mysql_error());
   }
   
   echo 'Connected successfully';
   mysql_close($conn);
?>

php_and_mysql.htm