'Varchar' ]; private static $has_one = [ 'CEO' => CEO::class, 'PreviousCEO' => CEO::class, 'Owner' => DataObject::class // polymorphic ]; private static $has_many = array( 'CurrentStaff' => Staff::class . '.CurrentCompany', 'PreviousStaff' => Staff::class . '.PreviousCompany' ); }