Query for date generating the months as well

Question

Hi Folks
I need your help to resolve th query below
I need to generate the sql query
example
YEAR MONTH count(EMPNO)
1981 JAN 0
FEB 2
MAR
DEC
I need to generate all the months and count of employee being hired for that month,where the month without any emp being hired should show as 0

Answer 1

Or perhaps...
SQL> WITH t AS (SELECT TO_DATE('01/01/2008','dd.mm.yyyy') AS dt, 1 AS eno FROM dual UNION ALL
  2             SELECT TO_DATE('01/01/2008','dd.mm.yyyy') AS dt, 2 FROM dual UNION ALL
  3             SELECT TO_DATE('01/02/2008','dd.mm.yyyy') AS dt, 3 FROM dual UNION ALL
  4             SELECT TO_DATE('01/06/2008','dd.mm.yyyy') AS dt, 4 FROM dual UNION ALL
  5             SELECT TO_DATE('01/03/2007','dd.mm.yyyy') AS dt, 3 FROM dual UNION ALL
  6             SELECT TO_DATE('01/05/2007','dd.mm.yyyy') AS dt, 4 FROM dual UNION ALL
  7             SELECT TO_DATE('01/02/2008','dd.mm.yyyy') AS dt, 5 FROM dual UNION ALL
  8             SELECT TO_DATE('01/12/2008','dd.mm.yyyy') AS dt, 6 FROM dual)
  9  -- END OF TEST DATA
10  SELECT EXTRACT(year FROM md.md) as year, EXTRACT(month FROM md.md) as month, count(t.dt) as cnt
11  FROM (select add_months(min_date,rownum-1) as md
12        from (select min(trunc(dt,'MM')) as min_date, max(trunc(dt,'MM')) as max_date from t)
13        connect by rownum <= months_between(max_date,min_date)+1) md
14       LEFT OUTER JOIN t ON (trunc(t.dt) = md.md)
15  GROUP BY EXTRACT(year FROM md.md), EXTRACT(month FROM md.md)
16  ORDER BY 1,2
17
SQL> /
      YEAR      MONTH        CNT
      2007          3          1
      2007          4          0
      2007          5          1
      2007          6          0
      2007          7          0
      2007          8          0
      2007          9          0
      2007         10          0
      2007         11          0
      2007         12          0
      2008          1          2
      2008          2          2
      2008          3          0
      2008          4          0
      2008          5          0
      2008          6          1
      2008          7          0
      2008          8          0
      2008          9          0
      2008         10          0
      2008         11          0
      2008         12          1
22 rows selected.
SQL>