Intresting query!!! may be for me...

Question

Hello Friends
Please can you help me with your query for the following table
SQL for Oracle 10g table containing following data
Table 1
slNo Project issueno date
1 Prj1 issue11 2000-1-19 - project 1 added
2 Prj1 issue12 2001-2-11
3 Prj1 issue13 2002-3-12
4 Prj1 issue14 2003-4-13
5 Prj1 issue15 2004-5-14
6 Prj1 issue16 2005-6-15
7 Prj2 issue21 2002-2-11 - project 2 added
8 Prj2 issue22 2003-3-1
9 Prj2 issue23 2004-3-1
10 Prj2 issue24 2005-4-1
11 Prj2 issue25 2006-5-1
12 Prj2 issue26 2007-6-1
13 Prj3 issue31 2003-1-10 - project 3 added
14 Prj3 issue32 2004-2-1
15 Prj3 issue33 2005-3-1
16 Prj3 issue34 2006-4-1
17 Prj3 issue35 2007-5-1
18 Prj3 issue36 2008-6-1
19 Prj4 issue41 2003-1-12 - project 4 added
20 Prj4 issue42 2004-2-13
21 Prj4 issue43 2005-3-14
22 Prj4 issue44 2006-4-15
23 Prj4 issue45 2007-5-16
24 Prj4 issue46 2008-6-17
Can you write the sql in oracle to find out the number of projects added in each month (YYYY-MM)
Assumption: A project is created on the same day as first issueno
Period(YYYY-Q) Count of Projects
2000-1          1
2000-2 0
2000-3 0
...... 0
..... 0
2002-1          1
...... 0
...... 0
2003-4          2
Can we get this using Group by ROLLUP or just group by?
Please post your query on reply, Your comments would be much appreciated

Answer 1

Yes I can write it. So can a lot of people. But this
is your schoolwork and you need to do it yourself.
You can do so using GROUP BY.Why make it simple when you can make it fun (especially bearing in mind the specification is to have 0's for the months without a project start)
SQL> ed
Wrote file afiedt.buf
  1  WITH table1 as (select 1 as slNo, 'Prj1' as Project, 'issue11' as issueno, to_date('2000-1-19','YYYY-MM-DD') as dt from dual union all
  2                  select 2, 'Prj1', 'issue12', to_date('2001-2-11','YYYY-MM-DD') from dual union all
  3                  select 3, 'Prj1', 'issue13', to_date('2002-3-12','YYYY-MM-DD') from dual union all
  4                  select 4, 'Prj1', 'issue14', to_date('2003-4-13','YYYY-MM-DD') from dual union all
  5                  select 5, 'Prj1', 'issue15', to_date('2004-5-14','YYYY-MM-DD') from dual union all
  6                  select 6, 'Prj1', 'issue16', to_date('2005-6-15','YYYY-MM-DD') from dual union all
  7                  select 7, 'Prj2', 'issue21', to_date('2002-2-11','YYYY-MM-DD') from dual union all
  8                  select 8, 'Prj2', 'issue22', to_date('2003-3-1','YYYY-MM-DD') from dual union all
  9                  select 9, 'Prj2', 'issue23', to_date('2004-3-1','YYYY-MM-DD') from dual union all
10                  select 10, 'Prj2', 'issue24', to_date('2005-4-1','YYYY-MM-DD') from dual union all
11                  select 11, 'Prj2', 'issue25', to_date('2006-5-1','YYYY-MM-DD') from dual union all
12                  select 12, 'Prj2', 'issue26', to_date('2007-6-1','YYYY-MM-DD') from dual union all
13                  select 13, 'Prj3', 'issue31', to_date('2003-1-10','YYYY-MM-DD') from dual union all
14                  select 14, 'Prj3', 'issue32', to_date('2004-2-1','YYYY-MM-DD') from dual union all
15                  select 15, 'Prj3', 'issue33', to_date('2005-3-1','YYYY-MM-DD') from dual union all
16                  select 16, 'Prj3', 'issue34', to_date('2006-4-1','YYYY-MM-DD') from dual union all
17                  select 17, 'Prj3', 'issue35', to_date('2007-5-1','YYYY-MM-DD') from dual union all
18                  select 18, 'Prj3', 'issue36', to_date('2008-6-1','YYYY-MM-DD') from dual union all
19                  select 19, 'Prj4', 'issue41', to_date('2003-1-12','YYYY-MM-DD') from dual union all
20                  select 20, 'Prj4', 'issue42', to_date('2004-2-13','YYYY-MM-DD') from dual union all
21                  select 21, 'Prj4', 'issue43', to_date('2005-3-14','YYYY-MM-DD') from dual union all
22                  select 22, 'Prj4', 'issue44', to_date('2006-4-15','YYYY-MM-DD') from dual union all
23                  select 23, 'Prj4', 'issue45', to_date('2007-5-16','YYYY-MM-DD') from dual union all
24                  select 24, 'Prj4', 'issue46', to_date('2008-6-17','YYYY-MM-DD') from dual)
25      ,proj_start as (select slNo, project, issueno, trunc(dt, 'MM') as dt
26                      from (select slNo, project, issueno, dt, min(issueno) over (partition by project) as min_issue
27                            from table1)
28                      where issueno = min_issue)
29      ,mm_dates as (select min(dt) as min_dt, max(dt) as max_dt from proj_start)
30      ,dates    as (select add_months(min_dt,rownum-1) as dt
31                    from mm_dates
32                    connect by rownum <= months_between(max_dt,min_dt)+1)
33  -- END OF TEST DATA
34  select to_char(d.dt, 'YYYY-MM') as dt, count(p.dt) as cnt
35  from dates d LEFT OUTER JOIN proj_start p ON (p.dt = d.dt)
36  group by to_char(d.dt, 'YYYY-MM')
37* order by 1
SQL> /
DT             CNT
2000-01          1
2000-02          0
2000-03          0
2000-04          0
2000-05          0
2000-06          0
2000-07          0
2000-08          0
2000-09          0
2000-10          0
2000-11          0
2000-12          0
2001-01          0
2001-02          0
2001-03          0
2001-04          0
2001-05          0
2001-06          0
2001-07          0
2001-08          0
2001-09          0
2001-10          0
2001-11          0
2001-12          0
2002-01          0
2002-02          1
2002-03          0
2002-04          0
2002-05          0
2002-06          0
2002-07          0
2002-08          0
2002-09          0
2002-10          0
2002-11          0
2002-12          0
2003-01          2
37 rows selected.
SQL>