validation set in PHP MySQL code for server side with example

Description

PHP Validation with Example for simple and short way complete reference PHP tutorial,  how to implement php validation for select dropdown, input value checkbox  select dropdown radio buttons . Form Validation Client And Server Side in php and fetch data for mysql ajax javascript JS set 

 Server Side validation in php

 

 client side validation in php with example set in javascript 

 server side validation in php with example set in core php

Condition apply if not Variable empty or not send

if ($courseroomselect!='undefined' && $topicselect!='') { 

write code

}

if (empty($_POST['tnumber']) || $_POST['rnumber'] !== '') {

write code

}