case when sums returning null values

Question

I've written the following temp table to set up for a case when sum query.

Total_count_package_5_15 and total_count_package_5_13 are both returning null values. (They shouldn't be). The data is properly set up in the preceding temporary table and I've confirmed that the data is there as expected.

create temporary table screening_packages_count_2018 as

select screening_screen_date,
       count(case when screening_package = 1 then 1 end) as count_package_1,
       count(case when screening_package = 2 then 1 end) as count_package_2,
       count(case when screening_package = 3 then 1 end) as count_package_3,
       count(case when screening_package = 4 then 1 end) as count_package_4

from prod.leasing_fact

where date_part(year, screening_screen_date) = 2018

group by screening_screen_date

order by 1;


-- 5 AND 6 PACKAGE TOTALS BASED ON 2018 1-4 COUNTS

    select date_trunc('day', screening_screen_date)                                              as day,
           case
               when (sum(count_package_1) + sum(count_package_2) + sum(count_package_3) <= 75)
                   then (sum(count_package_1) + sum(count_package_2) + sum(count_package_3)) end as total_count_package_5_15,

           case
               when ((sum(count_package_1) + sum(count_package_2) + sum(count_package_3)) >= 76 and
                     (sum(count_package_1) + sum(count_package_2) + sum(count_package_3)) <= 150)
                   then (sum(count_package_1) + sum(count_package_2) + sum(count_package_3)) end as total_count_package_5_13,

           0                                                                                     as total_count_package_6

    from screening_packages_count_2018

    where count_package_4 = 0
    group by day

I believe that there is an error in my case statement when using sums, but I'm not sure what is going on here. Thanks!

Answer 1

Try this... Put an ELSE 0 in the first Select for each Count() function . If there are any NULL values, you can't SUM NULL values.

create temporary table screening_packages_count_2018 as

select screening_screen_date,
       count(case when screening_package = 1 then 1 ELSE 0 end) as count_package_1,
       count(case when screening_package = 2 then 1 ELSE 0 end) as count_package_2,
       count(case when screening_package = 3 then 1 ELSE 0 end) as count_package_3,
       count(case when screening_package = 4 then 1 ELSE 0 end) as count_package_4

from prod.leasing_fact

where date_part(year, screening_screen_date) = 2018

group by screening_screen_date

order by 1;


-- 5 AND 6 PACKAGE TOTALS BASED ON 2018 1-4 COUNTS

    select date_trunc('day', screening_screen_date)                                              as day,
           case
               when (sum(count_package_1) + sum(count_package_2) + sum(count_package_3) <= 75)
                   then (sum(count_package_1) + sum(count_package_2) + sum(count_package_3)) end as total_count_package_5_15,

           case
               when ((sum(count_package_1) + sum(count_package_2) + sum(count_package_3)) >= 76 and
                     (sum(count_package_1) + sum(count_package_2) + sum(count_package_3)) <= 150)
                   then (sum(count_package_1) + sum(count_package_2) + sum(count_package_3)) end as total_count_package_5_13,

           0                                                                                     as total_count_package_6

    from screening_packages_count_2018

    where count_package_4 = 0
    group by day