How to get result from database on the change of values in text box using Ajax?

I am working in PHP and Mysql Combo

I need to search the results from DB and store in a hidden field , on change of the value user inserts in a text bo开发者_JS百科x.

How can I do this Using Ajax?

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You will need a few things:

• Your main page.
• A php file which processes the given input (the search string) and outputs only the value you want to store in the hidden field (returnsearchresults.php in the example below).
• Some javascript to make the ajax work.

I'd recommend using jQuery for the ajax though you could always roll your own if you're a masochist.

On your main page you will need something like this:

$("#ID_OF_SEARCH_BOX_GOES_HERE").keydown(function(event) {
    search_string = $("#ID_OF_SEARCH_BOX_GOES_HERE").val();
    $("#ID_OF_HIDDEN_FIELD_GOES_HERE").load("returnsearchresults.php?q="+search_string);
});

Edit: Here's an idea of what returnsearchresults.php should look like:

<?php
     $search_string = $_GET['q'];
     // ADD SOME CHECKS IN HERE TO PREVENT SQL INJECTION OR WHATEVER
     $SQL = "SELECT 
                 whatever_you_need, 
             FROM 
                 your_database 
             WHERE 
                 the_column 
             LIKE 
                 '%$q%'";
     $result = mysql_query($sql);
     while ($row = mysql_fetch_array($result))
     {
         echo $row[0], ', '; // obviously this line depends on how 
                             // you need to format your hidden field.
     }
?>

Note: I haven't included code to open/close the database connection or to verify that $_GET['q'] isn't malicious. I'll leave that up to you!