class Company extends Controller
{
public function show($id)
{
$list = Db::table('DataMessage D')
->distinct(true)
->field('D.Order,D.CreateTime,s.SystemName,m.AccidentDes,a.name')
->where('D.ProjectID',$id)
->join('FireSystem s','s.ID = D.SystemID')
->join('Message m','m.DataMsgID= D.ID')
->join('AccidentType a','m.AccidentType= a.ID')
->order('D.CreateTime desc')
->paginate(25);
$this->assign('list',$list);
return $this->fetch('Company/companyceil');
}
}

还是要看具体情况，可以考虑索引，分表等