Question

我有一个像这样的user表

FIRSTNAME  |  LASTNAME  |  ID  |
--------------------------------
James      |  Hay       |  1   |
Other      |  Person    |  2   |

我也有attendance这样的表

EVENTID  |  USERID  |  ATTENDANCE  |  STATUS  |
-----------------------------------------------
1           1          True           3
2           1          False          1
3           1          False          3
1           2          False          1
2           2          True           3
3           2          True           3

基本上，当用户被邀请参加某个活动时，会在attendance表中添加一行，其中包含事件ID，用户ID，错误出席率和状态0。

状态只是其回复的指标

0 = No Response
1 = Said No
2 = Said Yes
3 = Said yes and seats confirmed

我想从查询这两个表中得到的最终结果非常复杂，我无法弄清楚我需要做什么。

我想得到像这样的结果

NAME          |  % of saying YES to an RSVP  | % of attending after saying yes
-------------------------------------------------------------------------------
James Hay     |             66               |                50
Other Person  |             66               |                100

我确定你可以弄清楚我是如何获得这些数据但是要解释一下，James Hay对邀请的2/3赛事有3个（是）状态。所以说“是”的百分比是66.在他说“是”的2个中，他只是在参加“是50％”之后参加了1/2％

因为我无法理解这一点，所以在这里的任何推动都会非常受欢迎。

修改

同样重要的是，我希望结果包括数据库中的每个用户，即使它们在attendance表中有0行。

Answer 1

select
u.firstname, u.lastname
-- said yes, as percentage
,floor(100.0
    * count(case when a.status in (2,3) then 1 end)
    / count(u.id)) yes
-- attended after saying yes, as percentage
,floor(100.0
    * count(case when a.status in (2,3) and attendance='true' then 1 end)
    / nullif(count(case when a.status in (2,3) then 1 end),0)) attendance
--,count(u.id) rsvp -- total invites
from users u
left join attendance a on a.userid = u.id
group by u.firstname, u.lastname

注意：对于用户从未收到过邀请的特殊情况，统计信息显示为0％且为NULL。

条款说明：

count(case when a.status in (2,3) then 1 end)
- 表示他们说是，多次使用两次
count(u.id)
- 收到多少邀请（记录在案）。特殊情况是他们没有收到，在这种情况下LEFT JOIN使它成为1（不重要）
count(case when a.status in (2,3) and attendance='true' then 1 end)
- 在他们说“是”之后他们参加了多少次

Answer 2

SELECT A.NAME,B.PERCENTAGE_YES_RSVP,B.PERCENTAGE_AFTER_YES
FROM 
( 
  SELECT U.ID AS ID,U.FIRSTNAME+''+U.LASTNAME AS NAME
  FROM USERS U
) A,
(
  SELECT A.USERID,A.PERCENTAGE_YES_RSVP,B.PERCENTAGE_AFTER_YES
FROM   
  (
    SELECT B.USERID,ROUND((CAST(B.COUNT_YES_RSVP AS FLOAT)/B.TOTAL_COUNT)*100,0) AS PERCENTAGE_YES_RSVP    
    FROM  
    (SELECT A.USERID,
       SUM(CASE WHEN A.STATUS=3 THEN 1 END)AS COUNT_YES_RSVP,
       COUNT(*) AS TOTAL_COUNT
       FROM ATTENDANCE A  
       GROUP BY A.USERID
     ) B
  ) A,  
(
  SELECT C.USERID,(CAST(C.COUNT_AFTER_YES_RSVP AS FLOAT)/C.TOTAL_COUNT)*100 AS PERCENTAGE_AFTER_YES   
  FROM  
  (SELECT A.USERID,
       SUM(CASE WHEN A.STATUS=3 AND A.ATTENDANCE='TRUE' THEN 1 END)AS COUNT_AFTER_YES_RSVP,
       SUM(CASE WHEN A.STATUS=3 THEN 1 END) AS TOTAL_COUNT
   FROM ATTENDANCE A  
   GROUP BY A.USERID
   ) C
)B   
WHERE A.USERID=B.USERID
) B
WHERE A.ID = B.USERID;

Answer 3

修改

哎呀，忘了加入用户：）

select firstname, lastname, convert(decimal (5, 2), 1. * count(case when status in (2, 3) then 1 end) / count(*) * 100) SaidYes, convert(decimal (5, 2), 1. * count(case when status in (2, 3) and attendance = 'True' then 1 end) / count(case when status in (2, 3) then 1 end) * 100) ActuallyAttended from attendance a join users u on a.userid = u.id group by firstname, lastname

sql查询中的半复杂结果集

3 个答案: