1. Settings related to your php.ini file:
a) search the variable mssql.secure_connection in your php.ini file and put it to on mode if its off
b) remove comment from the dll extention php_mssql.dll (i.e. remove the ; from the front of the extention )
2. Settings related to the dll files.
download a file name ntwdblib.dll from the internet. you can download it from here or can search on internet for that. copy the downloaded dll to the apache/bin directory and for IIS copy it to the php extention directory (if path not known can be found in php.ini for variable extension_dir)
also you need to have your php_mssql.dll in your php extension directory. if its not present please download it and copy it to the default php extension directory can be found here.
3. restart all your services (i.e. php and apache or iis) and you can use the script given below to connect to your SQL Server.
<?php
$mssql_hostname = "(local)";
$mssql_user = "swadesh";
$mssql_password = "behera";
$mssql_database = "db";
$prefix = "";
$bd = mssql_connect($mssql_hostname, $mssql_user, $mssql_password) or die("Could not connect database");
mssql_select_db($mssql_database, $bd) or die("Could not select database");
?>
