CODEWITHSUNDEEP
mysqlsqldatabase
Patrick Kusebauch
Patrick Kusebauch

Reputation: 77

Calculating percentage over subselect SQL

I have a table that records events regarding email campaigns. I want to figure out the percentage of campaigns where there was more than one event happening for the campaign.

First I calculated the number of events happening in each campaign:

select count(*) as counter
               from campaigns_log
               where event IN ('send', 'open')
                 and campaign_id is not null
               group by campaign_id, email

Then I grouped the campaigns in the condition whether more than one event happened:

select count(counter) as occurences, IF(counter > 1, 2, 1) as grouper
         from (select count(*) as counter
               from campaigns_log
               where event IN ('send', 'open')
                 and campaign_id is not null
               group by campaign_id, email) as counters_table
         group by grouper

Sample result:

occurences ¦ grouper
132        ¦ 1
360        ¦ 2

Now I want to calculate for each row the percentage of total occurrences. So something like this:

occurences ¦ grouper ¦ percentage
132        ¦ 1       ¦ 132/(132+360)
360        ¦ 2       ¦ 360/(132+360)

I tried this, but it does not work, it does not properly calculate the sum total:

select *, occurences/(select sum(occurences))
from (
         select count(counter) as occurences, IF(counter > 1, 2, 1) as grouper
         from (select count(*) as counter
               from campaigns_log
               where event IN ('send', 'open')
                 and campaign_id is not null
               group by campaign_id, email) as counters_table
         group by grouper
     ) as occurences_table group by occurences, grouper

Any idea where is my mistake in the last step?

Upvotes: 0

Views: 35

Answers (1)

Zaynul Abadin Tuhin
Zaynul Abadin Tuhin

Reputation: 31991

use subquery for total count and divide

select a.occurences,a.grouper, (a.occurences/c.total) as percentage
from (select count(counter) as occurences, IF(counter > 1, 2, 1) as grouper
             from (select count(*) as counter
                   from campaigns_log
                   where event IN ('send', 'open')
                     and campaign_id is not null
                   group by campaign_id, email) as counters_table
             group by grouper
   ) a,
    (select sum(occurences) total from
    (select count(counter) as occurences, IF(counter > 1, 2, 1) as grouper
             from (select count(*) as counter
                   from campaigns_log
                   where event IN ('send', 'open')
                     and campaign_id is not null
                   group by campaign_id, email) as counters_table
             group by grouper
   ) b )c

Upvotes: 1

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