SQL Query Urgent..pls help

Question

Dear Experts,
Table.
C_id Purity
1     100
2     100
10     100
11     100
12     100
Ranking Regions by Size You have to list all regions in the table, and you have to list them according to their size.
you need to list all regions of two or more containers with a purity of 100, and you need to sort that list by the number of containers in each region.
The output should be something like this:
RegBeg RegEnd RegionSize
10 12 3
1 2 2
Kindly help me,
Basav

Answer 1

Looks like a homework assignment.
Perhaps you can explain to your tutor how the tabbibitosan method works...
SQL> ed
Wrote file afiedt.buf
  1  with t as (select 1 as C_id, 100 as Purity from dual union all
  2             select 2, 100 from dual union all
  3             select 4, 100 from dual union all
  4             select 5, 100 from dual union all
  5             select 6, 50 from dual union all
  6             select 7, 100 from dual union all
  7             select 10, 100 from dual union all
  8             select 11, 100 from dual union all
  9             select 12, 100 from dual)
10  --
11  -- use tabbibitosan method to group data
12  select min(c_id) as min_c_id
13        ,max(c_id) as max_c_id
14        ,count(*) as grp_size
15  from   t
16  where purity = 100
17  group by c_id-rownum
18  having count(*) > 1
19* order by 3 desc, 1
SQL> /
  MIN_C_ID   MAX_C_ID   GRP_SIZE
        10         12          3
         1          2          2
         4          5          2... if you can understand it. ;)