我現(xiàn)在的一個場景是，一個用戶表，一個用戶詳情信息表，還有一個行業(yè)表。用戶詳情里面的user_id對應用戶里面的id,用戶里面的hangye是數(shù)值，對用的是行業(yè)表里面的type_id，要取出type_name

   $user = DB::table('userinfo as b')
    ->rightJoin('users as a','a.id','=','b.user_id')
    ->rightJoin('kehuanli_type as c','c.type_id','=','b.hangye')
    ->where('a.id',$id)
    ->select('a.name','a.email','a.created_at','b.tel','b.address','c.type_name')
    ->get()->toArray();
      打開laravel的debugar工具
  select * from `users` where `users`.`id` = '7' limit 1

    select `a`.`name`, `a`.`email`, `a`.`created_at`, `b`.`tel`, `b`.`address`, `c`.`type_name` from `userinfo` as `b` right join `users` as `a` on `a`.`id` = `b`.`user_id` right join `kehuanli_type` as `c` on `c`.`type_id` = `b`.`hangye` where `a`.`id` = '7'

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2.查詢某個小時或者某天的信息day('time') hour('time')就可以取出一個時間格式的某天或者某小時

HAVING 子句
在 SQL 中增加 HAVING 子句原因是，WHERE 關鍵字無法與合計函數(shù)一起使用。

    SELECT Customer,SUM(OrderPrice) FROM Orders
WHERE Customer='Bush' OR Customer='Adams'
GROUP BY Customer
HAVING SUM(OrderPrice)>1500