Largest and 2nd largest number query group by clause doubt

Question

Hi, I have the following data in the database
deal id reporting date
12 6/1/2012
12 4/1/2012
12 2/1/2012
13 3/1/2012
13 2/1/2012
13 1/1/2012
I want for each deal id , the highest reporitng date and the 2nd highest reporting date...
i.e output
deal id date1 date2
12 6/1/2012 4/1/2012
13 3/1/2012 2/1/2012
I wrote the following query
select dealID,reportingDate from XYZ ,(select deal id , max(reportingDate)as d1 from XYZ) B
where
dealId=b.dealID
and reportingDate!=b.d1
order by reportingDate desc
the problem is it gets all reporting date but the highest one for each deal ID. I do not want all the dates to come. just the highest and second highest
plz help
Edited by: user7963410 on Sep 14, 2012 10:01 PM

Answer 1

Venkadesh wrote:
this ?This is one overcomplicated piece of code. And it is incorrect. First of all '6/1/2012' is a string, not a date, so ordering by it will produce incorrect results. For example (I assume '6/1/2012' is Januray 6, 2012), '6/1/2012' > '1/5/2012':
SQL> with t(id,reporting) as
  2  (
  3  select 12,'6/1/2012' from dual
  4  union all
  5  select 12,'4/1/2012' from dual
  6  union all
  7  select 12,'1/5/2012' from dual
  8  union all
  9  select 13,'3/1/2012' from dual
10  union all
11  select 13,'2/1/2012' from dual
12  union all
13  select 13,'1/1/2012' from dual
14  )
15  select id,regexp_substr(reporting,'\d+.\d+.\d+') date1,
16  regexp_substr(reporting,'\d+.\d+.\d+',1,2) date2
17  from (select id,listagg(reporting,' ') within group(order by reporting desc)
18   reporting from (select id,reporting
19   from (select id,reporting,row_number() over(partition by id order by reporting desc) rn
20  from t)
21  where rn<=2)
22  group by id)
23  /
        ID DATE1           DATE2
        12 6/1/2012        4/1/2012
        13 3/1/2012        2/1/2012
SQL> And code doesn't take into account id,reporting might have duplicates:
SQL> with t(id,reporting) as
  2  (
  3  select 12,'6/1/2012' from dual
  4  union all
  5  select 12,'6/1/2012' from dual
  6  union all
  7  select 12,'4/1/2012' from dual
  8  union all
  9  select 12,'2/1/2012' from dual
10  union all
11  select 13,'3/1/2012' from dual
12  union all
13  select 13,'2/1/2012' from dual
14  union all
15  select 13,'1/1/2012' from dual
16  )
17  select id,regexp_substr(reporting,'\d+.\d+.\d+') date1,
18  regexp_substr(reporting,'\d+.\d+.\d+',1,2) date2
19  from (select id,listagg(reporting,' ') within group(order by reporting desc)
20   reporting from (select id,reporting
21   from (select id,reporting,row_number() over(partition by id order by reporting desc) rn
22  from t)
23  where rn<=2)
24  group by id)
25  /
        ID DATE1           DATE2
        12 6/1/2012        6/1/2012
        13 3/1/2012        2/1/2012
SQL> Anyway, all we need is row_number and max:
select  id,
        reporting date1,
        prev_reporting date2
  from  (
         select  id,
                 reporting,
                 row_number() over(partition by id order by reporting desc) rn,
                 max(reporting) over(partition by id order by reporting range between unbounded preceding and 1/24/60/60 preceding) prev_reporting
           from  t
  where rn = 1
/For example:
with t(id,reporting) as
select 12,to_date('6/1/2012','dd/mm/yyyy') from dual
union all
select 12,to_date('6/1/2012','dd/mm/yyyy') from dual
union all
select 12,to_date('4/1/2012','dd/mm/yyyy') from dual
union all
select 12,to_date('2/1/2012','dd/mm/yyyy') from dual
union all
select 13,to_date('3/1/2012','dd/mm/yyyy') from dual
union all
select 13,to_date('2/1/2012','dd/mm/yyyy') from dual
union all
select 13,to_date('1/1/2012','dd/mm/yyyy') from dual
select  id,
        reporting date1,
        prev_reporting date2
  from  (
         select  id,
                 reporting,
                 row_number() over(partition by id order by reporting desc) rn,
                 max(reporting) over(partition by id order by reporting range between unbounded preceding and 1/24/60/60 preceding) prev_reporting
           from  t
  where rn = 1
        ID DATE1           DATE2
        12 06-JAN-12       04-JAN-12
        13 03-JAN-12       02-JAN-12
SQL> But I prefer:
select  id,
        reporting date1,
        Nth_highest_reporting date2
  from  (
         select  id,
                 reporting,
                 row_number() over(partition by id order by reporting desc) rn,
                 lead(reporting,:n - 1) over(partition by id order by reporting desc) Nth_highest_reporting
           from  (
                  select  distinct *
                    from  t
  where rn = 1
/Where :n is Nth highest. For example:
SQL> variable n number
SQL> exec :n := 2;
PL/SQL procedure successfully completed.
SQL> with t(id,reporting) as
  2  (
  3  select 12,to_date('6/1/2012','dd/mm/yyyy') from dual
  4  union all
  5  select 12,to_date('6/1/2012','dd/mm/yyyy') from dual
  6  union all
  7  select 12,to_date('4/1/2012','dd/mm/yyyy') from dual
  8  union all
  9  select 12,to_date('2/1/2012','dd/mm/yyyy') from dual
10  union all
11  select 12,to_date('1/1/2012','dd/mm/yyyy') from dual
12  union all
13  select 13,to_date('3/1/2012','dd/mm/yyyy') from dual
14  union all
15  select 13,to_date('2/1/2012','dd/mm/yyyy') from dual
16  union all
17  select 13,to_date('1/1/2012','dd/mm/yyyy') from dual
18  )
19  select  id,
20          reporting date1,
21          Nth_highest_reporting date2
22    from  (
23           select  id,
24                   reporting,
25                   row_number() over(partition by id order by reporting desc) rn,
26                   lead(reporting,:n - 1) over(partition by id order by reporting desc) Nth_highest_reporting
27             from  (
28                    select  distinct *
29                      from  t
30                   )
31          )
32    where rn = 1
33  /
        ID DATE1           DATE2
        12 06-JAN-12       04-JAN-12
        13 03-JAN-12       02-JAN-12
SQL> exec :n := 3;
PL/SQL procedure successfully completed.
SQL> /
        ID DATE1           DATE2
        12 06-JAN-12       02-JAN-12
        13 03-JAN-12       01-JAN-12
SQL> exec :n := 4;
PL/SQL procedure successfully completed.
SQL> /
        ID DATE1           DATE2
        12 06-JAN-12       01-JAN-12
        13 03-JAN-12
SQL> SY.