Question

I have two tables – cpm(cc, ad_id and cpm) and clicks(cc and ad_id).

When I run:

   SELECT cpm.ad_id, 
          COUNT(clicks.id) * cpm.cpm AS clicks_income     
     FROM cpm 
LEFT JOIN clicks on clicks.ad_id = cpm.ad_id and clicks.cc = cpm.cc
 GROUP BY cpm.ad_id, cpm.cc

I get:

ad_id | clicks_income
---------------------
1     | 271.00
1     | 2.60
2     | 238.00

now the result I want is:

ad_id | clicks_income
---------------------
1     | 273.60
2     | 238.00

How can I group by only cpm.ad_id and having the SUM of all cc?

When I remove the cpm.cc I get:

ad_id | clicks_income
---------------------
1     | 273.00
2     | 238.00

Answer 1

Don’t use COUNT(whatever) * acolumn, use SUM(AColumn) instead.
Also a LEFT JOIN doesn’t make sense here because a mismatch will just add NULL to the sum, which isn’t very helpful.

SELECT cpm.ad_id, SUM(cpm.cpm) AS clicks_income 
FROM cpm INNER JOIN clicks ON clicks.ad_id = cpm.ad_id AND clicks.cc = cpm.cc
GROUP BY cpm.ad_id