Question

我的SELECT查询如下所示需要插入到表wifi_user_analytic_dy中。

SELECT
  date(acctstarttime)
, round(avg(acctsessiontime),2)average_connected_ap 
, calledstationid 
FROM ( SELECT acctstarttime, acctsessiontime, calledstationid 
   FROM wifi_radacct 
   WHERE acctstoptime <> '' 
   and date(acctstarttime)= date_trunc('day', now()) -'1 day'::interval 
 )a 
group by calledstationid, date(acctstarttime)

基于查询的示例结果：

| date       | average_connected_ap | calledstationid |
| 2017-12-06 | 1000                 | publica         |
| 2017-12-06 |  800                 | tumis           |
| 2017-12-06 |  500                 | penyet          |

以上查询将根据日期和ap找到平均连接，并更新到表wifi_user_analytic_dy中。下面是表wifi_user_analytic_dy中的预期结果。

| date       |  ap      | average_connected_duration_ap |
| 2017-12-06 | publica  |     1000                      |
| 2017-12-06 | tumis    |      800                      |
| 2017-12-06 |  penyet  |      500                      |

我正在尝试从上面的SELECT查询中复制average_connected_ap数据，并在列average_connected_duration_ap更新表wifi_user_analytic_dy。下面的UPDATE查询未生成正确的结果。它将相同的值复制到所有ap。

如何更正此更新查询。

UPDATE wifi_user_analytic_dy B
SET avg_connected_duration_ap = ( select round(avg(wifi_radacct.acctsessiontime),2)
       from wifi_radacct
       where date(acctstarttime)= date_trunc('day', now()) -'1 day'::interval 
       )
FROM wifi_radacct A
WHERE A.calledstationid=B.ap and A.date(acctstarttime)= B.date
;

希望有人可以告诉我。

Answer 1

你可以使用CTE。类似的东西：

WITH C as 
( select 
   D.ap, D.bate,
   (select round(avg(wifi_radacct.acctsessiontime),2)
   from wifi_radacct
   where date(acctstarttime)= date_trunc('day', now()) -'1 day'::interval) as V
  FROM wifi_radacct A
  JOIN wifi_user_analytic_dy D
  ON A.calledstationid=D.ap and A.date(acctstarttime)= D.date
)
UPDATE wifi_user_analytic_dy B
SET avg_connected_duration_ap = V
FROM C where A.calledstationid=C.ap and A.date(acctstarttime)=C.date

但是你不需要子查询：

WITH C as 
( select 
   D.ap, D.bate,
   round(avg(A.acctsessiontime),2
   from wifi_radacct
   where date(acctstarttime)= date_trunc('day', now()) -'1 day'::interval) as V
  FROM wifi_radacct A
  JOIN wifi_user_analytic_dy D
  ON A.calledstationid=D.ap and A.date(acctstarttime)= D.date
  GROUP BY D.ap,D.date
)
UPDATE wifi_user_analytic_dy B
SET avg_connected_duration_ap = V
FROM C where A.calledstationid=C.ap and A.date(acctstarttime)=C.date

并且可能不需要加入。

使用子查询更新

1 个答案: