Counting null and non-null values in a single query

Question

I have a table

create table us
(
 a number
);

Now I have data like:

a
1
2
3
4
null
null
null
8
9

Now I need

Answer 1

Here is a quick and dirty version that works on Oracle :

select sum(case a when null then 1 else 0) "Null values",
       sum(case a when null then 0 else 1) "Non-null values"
from us

Answer 2

use ISNULL embedded function.

---

Answer 3

usually i use this trick

select sum(case when a is null then 0 else 1 end) as count_notnull,
       sum(case when a is null then 1 else 0 end) as count_null
from tab
group by a

Answer 4

Just in case you wanted it in a single record:

select 
  (select count(*) from tbl where colName is null) Nulls,
  (select count(*) from tbl where colName is not null) NonNulls 

;-)

Answer 5

In my case I wanted the "null distribution" amongst multiple columns:

SELECT
       (CASE WHEN a IS NULL THEN 'NULL' ELSE 'NOT-NULL' END) AS a_null,
       (CASE WHEN b IS NULL THEN 'NULL' ELSE 'NOT-NULL' END) AS b_null,
       (CASE WHEN c IS NULL THEN 'NULL' ELSE 'NOT-NULL' END) AS c_null,
       ...
       count(*)
FROM us
GROUP BY 1, 2, 3,...
ORDER BY 1, 2, 3,...

As per the '...' it is easily extendable to more columns, as many as needed

Answer 6

As i understood your query, You just run this script and get Total Null,Total NotNull rows,

select count(*) - count(a) as 'Null', count(a) as 'Not Null' from us;