mysqlcon.php

<?php

function mysqlquery($query,$dbcon,$returnValue = false){
  $result = $dbcon->query($query);

  if(!$result){
    die('There was an error running the query [' . $dbcon->error . ']');
  }

  //Do not use `fetch_assoc()` in INSERT query to prevent
  //`PHP Fatal error:  Call to a member function fetch_assoc() on a non-object` error.
  if($returnValue){
    return $result->fetch_assoc();
  }
}