Question

I DON’t want to count NULL values. Because NULL should not be equal to NULL.

Look at this query result: link

WITH temp as (
SELECT 'A' as master , 1 Col from dual
UNION SELECT 'A' , 3  from dual
UNION SELECT 'B' , 1 from dual
UNION SELECT 'B' , 2 from dual
UNION SELECT 'C' , 1 from dual
UNION SELECT NULL , 1 from dual
UNION SELECT NULL , 2 from dual)
SELECT
   master,
   count(Col) over (partition by master)
FROM
  temp

Answer 1

If you don’t want to filter out the rows where master IS NULL, you can do something like

SELECT master,
SUM( CASE WHEN master IS NULL
THEN 0
ELSE 1
END) OVER (PARTITION BY master)
FROM temp

SQL> ed
Wrote file afiedt.buf

  1  WITH temp as (
  2  SELECT 'A' as master , 1 Col from dual
  3  UNION SELECT 'A' , 3  from dual
  4  UNION SELECT 'B' , 1 from dual
  5  UNION SELECT 'B' , 2 from dual
  6  UNION SELECT 'C' , 1 from dual
  7  UNION SELECT NULL , 1 from dual
  8  UNION SELECT NULL , 2 from dual)
  9  SELECT master,
 10         SUM( CASE WHEN master IS NULL
 11                   THEN 0
 12                   ELSE 1
 13               END) OVER (PARTITION BY master)
 14*   FROM temp
SQL> /

M SUM(CASEWHENMASTERISNULLTHEN0ELSE1END)OVER(PARTITIONBYMASTER)
- -------------------------------------------------------------
A                                                             2
A                                                             2
B                                                             2
B                                                             2
C                                                             1
                                                              0
                                                              0