PostgreSQL sum doesn't not calculate sum as intended

Question

select distinct userid, SUM(device)  
from table 
where userid != '' 
group by userid, device;

 userid  | sum 
---------+-----
 a       |  12
 b       |   1
 c       |  10
 c       |  78

why there is a duplicate userid without no sum calculated. All devices have integer values

is column "device" of a numerical type?

rodolfo_r
– rodolfo_r

2021-03-16 00:48:13 +00:00
Commented Mar 16, 2021 at 0:48 — rodolfo_r
– rodolfo_r, Commented Mar 16, 2021 at 0:48

The Impaler · Accepted Answer · 2021-03-16 00:55:40Z

3

Because you are grouping by both userid and device. Remove the device from the GROUP BY.

Your query should look like:

select userid, SUM (device)  
from table 
where userid != '' 
group by userid;

Incidentally, I removed DISTINCT since you are already aggregating.

answered Mar 16, 2021 at 0:55

The Impaler

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