php - mysql Update query customize accroding if field is present -

i presently have data

$user=$postdata['user_name']; $phone_no=$postdata['phone_no'];  $qry = "update users set user_name = '$user', phone_no = '$phone_no' id = 1" 

i want update user_name if value present in $postdata['user_name'] same case phone_no , if data present in $phone_no phone_no should updated .

you have construct query in segments:

$user = $postdata['user_name']; $phone_no = $postdata['phone_no'];  $update = array(); if($user) {     $update[] = "user_name = '$user'"; }  if($phone_no) {     $update[] = "phone_no = '$phone_no'"; }  if(count($update)) {     $query = "update users set ";     $query .= implode(",", $update);     $query .= " id = 1"; }