/**
* select('column0, column1') => "SELECT column0, column1"
* select('column0', 'column1') => "SELECT column0, column1"
* @param string $columns
* @return \phprs\ezsql\rules\select\FromRule
*/
public function select($columns)
{
SelectImpl::select($this->context, $columns);
return new FromRule($this->context);
}