code: public function set($set)
      {
          if (is_array($set) === true) {
              $this->set = '';
              foreach ($set as $name => $value) {
                  $pos = stripos($name, '.');
                  if ($pos !== false) {
                      $this->set .= substr($name, $pos + 1);
                  } else {
                      $this->set .= $name;
                  }
                  $this->set .= ' = ' . $value . ', ';
              }
              $this->set = substr($this->set, 0, -2);
          } else {
              $this->set = $set;
          }
  
          return $this;
      }
docs: Set set clause.
  
  @param  array|string $set set clause
  @return Update       this