public function get_col($query = null, $x = 0)
{
if ($query) {
$this->query($query);
}
$new_array = [];
// Extract the column values
for ($i = 0, $j = count($this->last_result); $i < $j; $i++) {
$new_array[$i] = $this->get_var(null, $x, $i);
}
return $new_array;
}