Question

I need to check if a certain value ‘SheetNumber’ is in my mysql database dynamically. I have seen it done on popular web sites and I am trying to find a good tutorial to outline it for me. I am fairly new to Javascript but i know a lot of PHP.

I am anxious to learn how to do this.

• Chris

Answer 1

You will need to do this using Ajax. I recommend the Jquery library. Install it using the Jquery documentation, and then use something like the following:

Javascript:

function makeAjaxRequest() {    var url='script-that-checks-db.php';    $.get(url,{},verifyDb); }  function verifyDb(response) {     if (response==1)     {        //The value exists, do what you want to do here     }      else     {       //The value doesn't exist     } } 

You can have makeAjaxRequest() invoked when someone clicks a link, clicks a button, or anything else, e.g:

<a href='#' onclick='makeAjaxRequest();'>Check database</a> 

The php code of the file script-that-checks-db.php (of course, name it something different) will be responsible for checking the db. The code would look something like this.

PHP:

<?php  //Do the mysql query and find out if the value exists or not.  if ($exists==true)    echo '1'; //1 will indicate to javascript that the value exists. else    echo '0'; ?> 

You could also use JSON here rather than the 0/1 method, but because you are new I think this will be simple enough for you.

Hope this helps, if you have any questions feel free to ask. Also, feel free to change the function and file names.