Validate required field in php or server side validation in php if javascript failed by client side

//add this function on function.php or other give other file name you are including on php page

function checkRequiredPost($requiredField) {
    $numRequired = count($requiredField);
    $keys        = array_keys($_POST);
    $allFieldExist  = true;
   
    foreach($requiredField as $reqr)
   
    {
        if($_POST[trim($reqr)]==''){$allFieldExist=false;break;}
    }
   
    return $allFieldExist;
}

// use below code before insert/update  query

$required=array('txt_name','txt_password'); // add fields name you want to mandatory them like name,password etc.

if(isset($_POST['submit']) && checkRequiredPost($required))

{
 ////type your code or insert/update query

}