public function values($data)
{
if ($this->_type !== 'insert') {
throw new Exception('You cannot add values before defining columns to use.');
}
if (empty($this->_parts['insert'])) {
throw new Exception('You cannot add values before defining columns to use.');
}
$this->_dirty();
if ($data instanceof ValuesExpression) {
$this->_parts['values'] = $data;
return $this;
}
$this->_parts['values']->add($data);
return $this;
}