如何通过groupBy只获取到每个分类下的三条数据呢？

select c.id, c.name, 
    SUBSTRING_INDEX(group_concat(v.id order by v.updated_at desc), ',', 3) vids, 
    SUBSTRING_INDEX(group_concat(v.name order by v.updated_at desc), ',', 3) v_names 
from video v join category c on xx 
group by c.idCopy

select * from shop a where N > (select count(*) from shop b where b.shop_name = a.shop_name
 and a.price < b.price) order by a.shop_name,a.price desc;Copy

// 综艺
$queryOne = Video::with(['category:id,name'])->where("category_id","综艺分类id")->orderBy("updated_at", "desc")->limit(3)->select("*");

// 动漫
$queryTwo = Video::with(['category:id,name'])->where("category_id","动漫分类id")->orderBy("updated_at", "desc")->limit(3)->select("*");

// 纪录片
$queryThree = Video::with(['category:id,name'])->where("category_id","纪录片分类id")->orderBy("updated_at", "desc")->limit(3)->select("*");

// 联合查询
$list = $queryOne->unionAll($queryTwo)->unionAll($queryThree)->get();

Copy

$categories = Category::with([
    'video'=>function ($query) {
        $query->orderBy('updated_at', 'desc')->limit(3);
    }
])
->get()
->toArray();Copy

\DB::table('videos as a')
    ->select('*')
    ->whereRaw('3 > (SELECT COUNT(*) FROM videos as b WHERE b.category_id = a.category_id AND b.updated_at > a.updated_at)')
    ->orderBy('a.category_id')
    ->orderByDesc('a.updated_at')
    ->get();

DB::table('videos as a')
    ->select('a.*')
    ->leftJoin('videos as b', function ($join){
        $join->on('a.category_id', '=', 'b.category_id')
            ->on('a.updated_at', '<', 'b.updated_at');
    })
    ->groupBy('a.id')
    ->havingRaw('COUNT(b.id) < 3')
    ->orderBy('a.category_id')
    ->orderByDesc('a.updated_at')
    ->get();Copy