code: public function addColumn(string $name, $value)
      {
          $this->args[] = $value;
          if (count($this->args) > 1) {
              $this->setColumnsValues .= ", ";
          }
          $argNum = count($this->args);
          $this->setColumnsValues .= "$name = \$".$argNum;
      }
docs: adds column to update query
  @param string $name
  @param $value