Help required with Analytic function

Question

Hi I have a table like following
column1 column2 column3 cloumn4 start_Date
1 601 A B 10-jan-2007
2 601 A B 11 -jan-2007
1 602 A B 12-jan-007
1 603 A C 12-jan-2007
there is no Uk on this table.
now I have to group column2 ,column3 ,column4.
I finally need to get the row that has highest start date. Effectively meaming
there will be three groups based on abouve data:
1st is:
1 601 A B 10-jan-2007
2 601 A B 11 -jan-2007
2nd is
1 602 A B 12-jan-007
3rd is
1 603 A C 12-jan-2007
now i need to get the second row from the first group only
2 601 A B 11 -jan-2007
i dont need data from other groups since they have less than 2 rows.
How can I achieve this using analytics function.
Please help!!

Answer 1

Hi,
Can you please provide an example. I am sorry, this
is my first day with analytice :(I figured as much; that's why I gave you detailed instructions to gain some experience by building on the
query that Forms already gave you (slightly prettied up below):
select  *
from    (   -- Begin sub-query
        SELECT  column1,column2,column3,column4
        ,        row_number () over
                    ( partition by column2,column3,column4
                      order by start_date desc
                    ) as rnk  -- "rank" is not a good name
        from   table
        )   -- End sub-query
where   rnk = 1;
[pre]
Follow the instructions I gave you earlier.
Add the analytic "COUNT (*) OVER (...) AS cnt" function next to the analytic ROW_NUMBER function in Forms' query.
Add the test for "cnt >= 2" next to the test for "rnk = 1".