'HTML' form

     <form  action="result.php" method="POST">

  <input type="search" name="query" size="10" id="searchfield" title="searchfield" />
  <input type="submit" name="Search" value="" alt="Search" id="searchbutton" title="Search" />
 </form>

result php file

<?php 
@session_start(); 
include 'connections.php';
if (isset($_POST['query']) && $_POST['query'] != "")


$query = $_POST['query'];

$min_length = 1;
if(strlen($query) >= $min_length)
  {
$query = htmlspecialchars($query);
$query = mysql_real_escape_string($query);
............`

value that entered in search field is not going from 'HTML' form to 'PHP' file to perform required operations please anyone help me to solve this bug..

It looks okay to me, try var_dump($_POST) on your results.php page to be positive.

I want to point out also, the original mysql functions are now deprecated in PHP and you should be using mysqli or PDO for your database connections.
http://php.net/manual/en/migration55.deprecated.php

Thank you very much for your reply I checked my code as your suggestion.. but it is printing NULL even though I am passing value...

$query = var_dump($_POST['$query']);
echo $query;

and it is printing 'NULL' @pixelsoul

Check the name of the action file.when you post the data it do not find the file name that you given.

action is finding 'result.php' file I checked by placing echo statments....@Sikkander Nasar