Question

I have the following sql which selects the most recurring row first based on the column “reported”

 $datan = mysql_query("
   SELECT *, COUNT(reported) AS ct
   FROM profile_reports
   WHERE open = '1'
   GROUP BY reported
   ORDER BY ct DESC
   LIMIT 1
 ") or die(mysql_error());

I want my sql to also check which ‘reporter’ (each is a number associated with a user) has the best percentage of useful reports, which is determined this way:

((raction > 0 AND raction < 99 AND open = '0' AND reporter = 'reporter') / (reporter = 'reporter' AND open = '0')) * 100

…and show the rows with highest percentage first. It’s a little tricky because no initial reporter is set.

Here’s a sample table:

+----+----------+----------+-------+----------+
| id | reporter | reported | open  |  raction |
+----+----------+----------+-------+----------+
|  1 |       24 |    26    |  0    |  3       |
|  2 |       24 |    23    |  0    |  0       |
|  3 |       24 |    29    |  1    |          |
|  4 |       12 |    29    |  0    |  4       |
|  5 |       12 |    29    |  1    |          |
|  6 |       24 |    21    |  1    |  0       |
+----+----------+----------+-------+----------+

I want it to see that there are more reports about user 29(column: reported), then check which reporting user(column: reporter) has the best percentage (based on the line of code above), in this case user 12, and display their report

Answer 1

Its actually pretty easy in just take the sums of your conditions and divide. In order to get the “Reported” correctly you’ll need to use an inline view to find the highest report.

SELECT pr.*, 
       ( Sum(pr.raction > 0 
             AND pr.raction < 99 
             AND pr.open = '0' 
             AND pr.reported = t.reported) / Sum(pr.reported = t.reported 
                                                 AND pr.open = '0') ) * 100 AS 
       usefull 
FROM   profile_reports pr, 
       (SELECT reported 
        FROM   profile_reports 
        WHERE  open = '1' 
        GROUP  BY reported 
        ORDER  BY Count(reported) DESC 
        LIMIT  1) t 
GROUP  BY reporter 
ORDER  BY usefull DESC 
LIMIT  1 

demo

Output

| ID | REPORTER | REPORTED | OPEN | RACTION | USEFULL |
-------------------------------------------------------
|  4 |       12 |       29 |    0 |       4 |     100 |

I haven’t done everything for you. You will have to decide what to do if the divisor is zero

Note in just about everything but MySQL you would need to use CASE

   SUM ( CASE WHEN raction > 0 AND .... THEN 1 ELSE 0 END) / ....