Calculate the date interval in days

Question

Hi all!
I need your kind help.
I have an oracle sql table.
here is goes..
TABLENAME: RACE
DATE NAME
11-JAN-12 JAMES
12-JAN-12 JAMES
14-JAN-12 JAMES
17-JAN-12 JAMES
22-JAN-12 JAMES
01-FEB-12 JOHN
11-FEB-12 JOHN
13-FEB-12 JOHN
14-FEB-12 JOHN
28-FEB-12 JOHN
01-MAR-12 JOHN
HOW DO I Calculate the total date interval(difference) for James and John in days?
for example in this case the total is 7 days for James(11-JAN-12 to 12-JAN-12 is 0 days and 12-JAN-12 to 14-JAN-12 is 1 day and 14-JAN-12 to 17-JAN-12 is 2 days) and 24 days for John
The data for the date will be random and can be up to 60 difference dates and names so I will like to calculate for all different names.. Thanks!

Answer 1

Can you explain in more detail why James should have 7 days?
Difference in dates can be easily calculated (if you use the DATE datatype, that is) by simply subtracting them.
Example:
SQL> -- generating sample data:
SQL> with race as (
  2  select to_date('11-JAN-12', 'dd-mon-yy') dt, 'JAMES' nm from dual union
  3  select to_date('12-JAN-12', 'dd-mon-yy'), 'JAMES' from dual union
  4  select to_date('14-JAN-12', 'dd-mon-yy'), 'JAMES' from dual union
  5  select to_date('17-JAN-12', 'dd-mon-yy'), 'JAMES' from dual union
  6  select to_date('22-JAN-12', 'dd-mon-yy'), 'JAMES' from dual union
  7  select to_date('01-FEB-12', 'dd-mon-yy'), 'JOHN' from dual union
  8  select to_date('11-FEB-12', 'dd-mon-yy'), 'JOHN' from dual union
  9  select to_date('13-FEB-12', 'dd-mon-yy'), 'JOHN' from dual union
10  select to_date('14-FEB-12', 'dd-mon-yy'), 'JOHN' from dual union
11  select to_date('28-FEB-12', 'dd-mon-yy'), 'JOHN' from dual union
12  select to_date('01-MAR-12', 'dd-mon-yy'), 'JOHN' from dual
13  )
14  --
15  -- actual query:
16  --
17  select max(dt)-min(dt) diff
18  ,      nm
19  from   race
20  group by nm;
      DIFF NM
        29 JOHN
        11 JAMESHowever, that is not your desired resultset. We (at least: I) need a bit more explanation why James should have 7 as date difference...
Also: DATE and NAME ar not suitable as column names.