Example php search script returning results as JSON/JSONP. See also https://gist.github.com/dsmeringe/5134955 for "queryClass"

quicksearch.php

<?php
/**
 * Search support for websites using JSON/JSONP.
 * Built to be used with a jquery ui autocomplete field.
 * 
 * This example is slightly generalized compared to it's original..
 * 
 * Search parameter for search values is 'term', like
 * quicksearch.php?term=search-value
 * 
 * supply parameter 'callback=callbackFuncName' to supply a jsonp callback function. 
 * 
 * @author David Smeringe <david@merea.se>
 */
header('content-type: application/json; charset=utf-8');
header("access-control-allow-origin: *");//remove if cross domain shouldn't be allowed

//get input values, generalize to support both get and post
$GP = isset($_GET['term'])? $_GET : $_POST;

//terminate with empty result if we don't have any search value
if (!isset( $GP['term'])) {
  exit (json_encode(array()));
}

//initalize storage - where we got our data
require_once('queryClass.php');
$queryObj;
try {
	$queryObj = new queryClass();
} catch (Exception $e) {
	//handle errors
	exit(json_encode($e->getMessage()));
}
$queryObj->hitsLimit = 15;
$queryObj->externalDBSettingsFile = 'connect.php';//holds db credentials
$queryObj->limitToLanguage = isset($GP['lang'])? $GP['lang']:0;//swedish?
if (isset($GP['hitslimit']) && $GP['hitslimit']<=300)
	$queryObj->hitsLimit = $GP['hitslimit'];

try {
	$queryObj->initializeDB();
	
	//destroyer command
	//drop old cached data?
	if (isset($GP['destroyer'])) {
		$k = $queryObj->dropStorageTable ();
		exit(json_encode($k?"dropped the data" : "didn't drop"));
	}
	
	//search? (returns an array of results)
	$result = $queryObj->search( $GP['term'], null, queryClass::GROUPSEARCH_SEARCHKEY);
	$retval = array();
 	//return all columns?
	if (isset($GP['returnFullHit'])) {
		$retval = $result;
	} else { //create a label/value list
		foreach ($result as $r) {
			$retval[] = array('label'=>$r['searchkey'], 'value'=>$r['searchkey']);
		}
	}
	
	//retun a JSON string
	$json = json_encode($retval);
	if (!isset($GP['callback']))
		exit( $json);
	if (is_valid_callback($GP['callback']))
		exit( $_GET['callback'] . '('.$json.')');
	
} catch (Exception $e) {
	die(json_encode($e->getMessage()));
}

unset($queryObj);

// something went wrong if we end up here..
// bad request
header('status: 400 Bad Request', true, 400);




/**
 * Validate JSON callback function
 * 
 * @param string $subject
 * @return boolean
 */
function is_valid_callback($subject)
{
    $identifier_syntax
      = '/^[$_\p{L}][$_\p{L}\p{Mn}\p{Mc}\p{Nd}\p{Pc}\x{200C}\x{200D}]*+$/u';

    $reserved_words = array('break', 'do', 'instanceof', 'typeof', 'case',
      'else', 'new', 'var', 'catch', 'finally', 'return', 'void', 'continue',
      'for', 'switch', 'while', 'debugger', 'function', 'this', 'with',
      'default', 'if', 'throw', 'delete', 'in', 'try', 'class', 'enum',
      'extends', 'super', 'const', 'export', 'import', 'implements', 'let',
      'private', 'public', 'yield', 'interface', 'package', 'protected',
      'static', 'null', 'true', 'false');

    return preg_match($identifier_syntax, $subject)
        && ! in_array(mb_strtolower($subject, 'UTF-8'), $reserved_words);
}
?>