分块处理 ``` Flight::where()->chunk(200, function ($flights) use() { foreach ($flights as $flight) { // 逻辑处理 } }); ``` 数据去重 ``` $users = DB::table('users')->distinct()->get(); $users=DB::table('users')->select('name')->distinct()->get(); $users=DB::table('users')->select('status','name')->distinct()->get(); ```