Question

I have a user table like this

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

I also have an attendance table like this

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

Basically, when a user is invited to an event, a row is added to the attendance table which has the event ID, their user ID, false attendance, and status 0.

Status is just an indicator of their response

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

My end result I want to get from querying these two tables is quite complicated and I can’t figure out what I need to do.

I want to get a result like this

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

I’m sure you can work out how I got those numbers but to explain, James Hay had the 3 (yes) status to 2/3 events invited to. So % of saying yes is 66. Out of the 2 he said yes to, he only attended 1/2 so % of attending after saying yes is 50%

Any push in the right track would be much appreciated here since I can’t get my head around this.

EDIT:

Also something quite important is that I want the results to include every user in the database even if they have 0 rows in the attendance table.

Answer 1

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;