laravel 多条件搜索操作 keyword

$keyword=$request->input();

$list = DB::table("user as a")

    ->leftJoin('students as b', 'b.id', '=',  'a.sid')

->where(function($query) use($keyword) {

        if(!empty($keyword["keyword"])){

            $name=$keyword["keyword"];

            $query->Where('user_name','like',"%$name%");

            $query->orWhere('alias_name','like',"%$name%");

            $query->orWhere('mobile','like',"%$name%");

        }

})

    ->where(function($query) use($keyword) {

    if(!empty($keyword["mid"])){

        $query->where('mid',$keyword["mid"]);

    }

})

    ->select(['b.*',,'b.id as b_id','a.*','a.id as a_id','a.name as a_name','b.name as b_name'])

    ->orderBy("a.id","desc")

    ->paginate(15);

写多个where是避免条件查询出错