<?php
$objConnect = mssql_connect("localhost","usr","pass");

if($objConnect)
{
  echo "Database Connected.<br />";
  echo mssql_error();
}
else
{
  echo "Database Connect Failed.<br />";
}

mssql_close($objConnect);
?>

$objConnect = mssql_connect("localhostSQLEXPRESS","usr","pass");

$objConnect = mssql_connect("localhostInstanceName","usr","pass");

$objConnect = mssql_connect("192.168.5.22SQLEXPRESS","usr","pass");
$objConnect = mssql_connect("192.168.5.22NamedInstance","usr","pass");
$objConnect = mssql_connect("192.168.5.22","usr","pass");

if($objConnect)
{
  echo "Database Connected.<br />";
  echo mssql_error();
}
else
{
  echo "Database Connect Failed.<br />";
}

if($objConnect)
{
  echo "Database Connected.<br />";
}
else
{
  echo "Database Connect Failed.<br />";
  echo mssql_error();
}