public function clean() { \Parameter::whereNotExists(function ($q) { $q->select(DB::raw(1))->from('Simulation_Parameter')->whereRaw('Simulation_Parameter.ParameterId = Parameter.Id'); })->whereNotExists(function ($q) { $q->select(DB::raw(1))->from('Simulation_Needle_Parameter')->whereRaw('Simulation_Needle_Parameter.ParameterId = Parameter.Id'); })->whereNotExists(function ($q) { $q->select(DB::raw(1))->from('Parameter_Attribution')->whereRaw('Parameter_Attribution.Parameter_Id = Parameter.Id'); })->delete(); }