MYSQL sum() for distinct rows

Question

I\'m looking for help using sum() in my SQL query:

SELECT links.id, 
       count(DISTINCT stats.id) as clicks, 
       count(DISTINCT conversions.id) as con         


        

Answer 1

This will do the trick, just divide the sum with the count of conversation id which are duplicate.

SELECT a.id,
       a.clicks,
       SUM(a.conversion_value/a.conversions) AS conversion_value,
       a.conversions
FROM (SELECT links.id, 
       COUNT(DISTINCT stats.id) AS clicks, 
       COUNT(conversions.id) AS conversions, 
       SUM(conversions.value) AS conversion_value 
      FROM links 
      LEFT OUTER JOIN stats ON links.id = stats.parent_id 
      LEFT OUTER JOIN conversions ON links.id = conversions.link_id 
      GROUP BY conversions.id,links.id
      ORDER BY links.created DESC) AS a
GROUP BY a.id

Answer 2

Select sum(x.value) as conversion_value,count(x.clicks),count(x.conversions)
FROM
(SELECT links.id, 
       count(DISTINCT stats.id) as clicks, 
       count(DISTINCT conversions.id) as conversions,
       conversions.value,       
FROM links 
LEFT OUTER JOIN stats ON links.id = stats.parent_id 
LEFT OUTER JOIN conversions ON links.id = conversions.link_id 
GROUP BY conversions.id) x
GROUP BY x.id 
ORDER BY x.created desc;

I believe this will give you the answer that you are looking for.

Answer 3

I use a subquery to do this. It eliminates the problems with grouping. So the query would be something like:

SELECT COUNT(DISTINCT conversions.id)
...
     (SELECT SUM(conversions.value) FROM ....) AS Vals

Answer 4

Use the following query:

SELECT links.id
  , (
    SELECT COUNT(*)
    FROM stats
    WHERE links.id = stats.parent_id
  ) AS clicks
  , conversions.conversions
  , conversions.conversion_value
FROM links
LEFT JOIN (
  SELECT link_id
    , COUNT(id) AS conversions
    , SUM(conversions.value) AS conversion_value
  FROM conversions
  GROUP BY link_id
) AS conversions ON links.id = conversions.link_id
ORDER BY links.created DESC

Answer 5

Jeromes solution is actually wrong and can produce incorrect results!!

sum(conversions.value)*count(DISTINCT conversions.id)/count(*) as conversion_value

let's assume the following table

conversions
id value
1 5
1 5
1 5
2 2
3 1

the correct sum of value for distinct ids would be 8. Jerome's formula produces:

sum(conversions.value) = 18
count(distinct conversions.id) = 3
count(*) = 5
18*3/5 = 9.6 != 8

Answer 6

How about something like this:

select l.id, count(s.id) clicks, count(c.id) clicks, sum(c.value) conversion_value
from    (SELECT l.id id, l.created created,
               s.id clicks,  
               c.id conversions,  
               max(c.value) conversion_value                    
        FROM links l LEFT
        JOIN stats s ON l.id = s.parent_id LEFT
        JOIN conversions c ON l.id = c.link_id  
        GROUP BY l.id, l.created, s.id, c.id) t
order by t.created