how_to_use.php

<?php
// ..... all other code ---
// Assuming database is connected
$k = $_POST['search_key'];
// Assuming $k is the search key

//include __DIR__ .'<path to lib.search.php>'
// i.e include the search library here
include __DIR__ .'/lib.search.php';

$s = new msearch($k);
$result = $s->getResult();

// This will have the search result

lib.search.php

<?php
/**
 * Code to search though the database against a key
 * and get result in sorted order
 *
 * Author: Minhaz A V <minhazav@gmail.com>
 */


// To avoid multiple redeclarations
if (!defined('_LIB_SEARCH')) {
	define('_LIB_SEARCH', 'defined');

	// Assumes database is connected

	class msearch {

		// --------------------------------------------------------------
		// --- class variables here ---
		// --------------------------------------------------------------

		// The search key used
		public $key = '';
		public $Ki, $Wi;

		// General things
		public $_general_terms = array('dr', 'in', 'at', 'from', 'on', ',', '.', 'doctor');

		// Categories of entities
		public $_categories = array('name', 'location', 'specialisation', 'pincode', 'general');

		// Current default weightage to each category
		public $_d_priority = array(1.1, 1, 1, 1, 0);

		// priority alloted to each in runtime
		public $_priority = array(1.1, 1, 1, 1, 0);

		// Doctors
		public $Di = array();
		public $Di_m = array();


		// --------------------------------------------------------------
		// --- member functions from here ---
		// --------------------------------------------------------------

		// constructor
		public function __construct($key) {
			$this->key = self::itrim(strtolower($key));

			// Split the key by space
			$this->Ki = self::mysql_filter(explode(' ', $this->key));

			// weightage array
			$this->Wi = array();

			$this->gather();
		}

		private function gather() {
			// Identify the category for each Ki
			foreach ($this->Ki as $key => $value) {
			    $this->Wi[] = array(0, 0, 0, 0, 0);

			    if (in_array($value, $this->_general_terms)) {
			        // only possiblity its a general term
			        $this->Wi[$key][4] = 1;
			        if ($value == 'dr' || $value == 'doctor') {
			            $this->_priority = $this->_d_priority;
			            $this->_priority[0] = $this->_d_priority[0] + .5;
			        } else if ($value == 'from') {
			            $this->_priority = $this->_d_priority;
			            $this->_priority[1] = $this->_d_priority[1] + .5;
			        }
			    } else {
			        if (is_numeric($value) && strlen($value) == 6) {
			            // only possiblity pincode

			            $query = mysql_query("SELECT id FROM `users` WHERE `type` = 'DOCTOR' AND `pin` LIKE '%$value%'");

			            $has_result = false;
			            while ($row = mysql_fetch_array($query)) {
			                if (!isset($this->Di[$row['id']])) {
			                    $this->Di[$row['id']] = $this->_priority[3];
			                    $this->Di_m[$row['id']] = array(0,0,0,1,0);
			                }
			                else {
			                    $this->Di[$row['id']] += $this->_priority[3];
			                    $this->Di_m[$row['id']][3] = 1;
			                }

			                $has_result = true;
			            }
			            $this->Wi[$key][3] = ($has_result) ? 1 : 0;
			        } else {
			            // Now get count and get weightage for different things
			            // name
			            $query = mysql_query("SELECT id FROM `users` WHERE `type` = 'DOCTOR' AND `name` LIKE '%$value%'");
			            $has_result = false;
			            while ($row = mysql_fetch_array($query)) {
			                if (!isset($this->Di[$row['id']])) {
			                    $this->Di[$row['id']] = $this->_priority[0];
			                    $this->Di_m[$row['id']] = array(1,0,0,0,0);
			                }
			                else {
			                    $this->Di[$row['id']] += $this->_priority[0];
			                    $this->Di_m[$row['id']][0] = 1;
			                }

			                $has_result = true;
			            }
			            $this->Wi[$key][0] = ($has_result) ? 1 : 0;

			            // location
			            $query = mysql_query("SELECT id FROM `users` WHERE `type` = 'DOCTOR' AND 
			                (`addrline1` LIKE '%$value%' OR `addrline2` LIKE '%$value%' OR
			                    `city` LIKE '%$value%' OR `state` LIKE '%$value%')");
			            $has_result = false;
			            while ($row = mysql_fetch_array($query)) {
			                if (!isset($this->Di[$row['id']])) {
			                    $this->Di[$row['id']] = $this->_priority[1];
			                    $this->Di_m[$row['id']] = array(0,1,0,0,0);
			                }
			                else {
			                    $this->Di[$row['id']] += $this->_priority[1];
			                    $this->Di_m[$row['id']][1] = 1;
			                }

			                $has_result = true;
			            }
			            $this->Wi[$key][1] = ($has_result) ? 1 : 0;

			            // TODO: specialisation
			        }
			    }

			    $sum = array_sum($this->Wi[$key]);
			    foreach ($this->Wi[$key] as $k => $v) {
			        $this->Wi[$key][$k] = ($sum != 0) ? intval($v) / intval($sum) : 0;
			    }
			}
		}

		public function getResult() {
			// Sort result by score
			arsort($this->Di);

			$result = array();
			foreach ($this->Di as $key => $value) {
			    $query = mysql_query("SELECT `name`, addrline1, addrline2, city, state, pin FROM `users` WHERE type = 'DOCTOR' AND id = '$key'; ");

			    if (!mysql_num_rows($query)) continue;
			    $row = mysql_fetch_array($query);

			    $t = array(
			    		'key' => $key,
			    		'score' => $value,
			    		'name' => $row['name'],
			    		'addrline1' => $row['addrline1'],
			    		'addrline2' => $row['addrline2'],
			    		'city' => $row['city'],
			    		'state' => $row['state'],
			    		'pin' => $row['pin']
			    	);
			    $result[] = $t;
			}

			return $result;
		}

		// --------------------------------------------------------------
		// --- static methods from here ---
		// --------------------------------------------------------------


		// Function to remove multiple consecutive spaces from search key
		private static function itrim($k) {
			$k = trim($k);
		    $len = strlen($k);
		    $j = 1;
		    for ($i = 1; $i < $len; $i++) {
		        if ($k[$i] == ' ' && $k[$i-1] == ' ') {
		            continue;
		        } else {
		            $k[$j++] = $k[$i];
		        }
		    }
		    $k[$j] = '\0';
		    return substr($k, 0, $j);
		}

		// Filter each element of array from mysql injection attack
		private static function mysql_filter($Ki) {
			$t = array();
			foreach ($Ki as $key => $value) {
				$t[] = mysql_real_escape_string($value);
			}
			return $t;
		}
	};
}

search_result_format

array (size=249)
  0 => 
    array (size=8)
      'key' => int 5919
      'score' => float 4.1
      'name' => string 'RAVINDRA KUMAR GUPTA' (length=20)
      'addrline1' => string 'RAVINDRA HOSPITAL AND HEART CENTRE' (length=34)
      'addrline2' => null
      'city' => string 'HISAR' (length=5)
      'state' => string 'haryana' (length=7)
      'pin' => string '125001' (length=6)
  1 => 
    array (size=8)
      'key' => int 2591
      'score' => float 3.1
      'name' => string 'Ravi  Ghai' (length=10)
      'addrline1' => string 'H.No. 529 Sector 2 ' (length=19)
      'addrline2' => null
      'city' => string 'Panchkula' (length=9)
      'state' => string 'Haryana' (length=7)
      'pin' => string '134109' (length=6)
  2 => 
    array (size=8)
      'key' => int 3664
      'score' => float 3.1
      'name' => string 'Ravi Kant Bhisham' (length=17)
      'addrline1' => string 'Bhisham Hospital ' (length=17)
      'addrline2' => null
      'city' => string 'Bhiwani' (length=7)
      'state' => string 'Haryana' (length=7)
      'pin' => string '127021' (length=6)
  3 => 
    array (size=8)
      'key' => int 4145
      'score' => float 2.6
      'name' => string 'Ravindranath Tagore Nallamotho' (length=30)
      'addrline1' => string 'Ravi Cardiac Diabetic Care Centre' (length=33)
      'addrline2' => null
      'city' => string 'Ponnur' (length=6)
      'state' => string 'Andhra Pradesh' (length=14)
      'pin' => string '522124' (length=6)
  4 => 
    array (size=8)
      'key' => int 1921
      'score' => float 2.6
      'name' => string 'Pravin Lahuji Nitnavare' (length=23)
      'addrline1' => string '"PRAVIN L NITNAVARE' (length=19)
      'addrline2' => null
      'city' => string ' DR. AMBEDKAR ROAD' (length=18)
      'state' => string 'NAGAUR' (length=6)
      'pin' => string ' INDORA"' (length=8)