SQL check if group contains NULL

Another possibility which doesn't use the fact that count(value) ignores NULL values:

select id, 
       sum(case when value is null then 1 else 0 end) as null_count
from your_table
group by id;

try

select id, 
       count(*) - count(value) as null_value_count
from your_table
group by id

SQLFiddle demo

Related