如何在sql中检索上个月的最新日期和本月的最新日期

Question

create table imsi_data(account varchar2(20)not null,imsi number(10),seqno number(20) not null,package_id number(10),event_date date)

insert into imsi_data values('10001',123456,09,164,add_months((sysdate),-2));
insert into imsi_data values('10001',123456,09,164,add_months((sysdate-1),-2));
insert into imsi_data values('10001',123456,09,164,add_months((sysdate-2),-2));
insert into imsi_data values('10001',123456,10,165,add_months((sysdate),-1));
insert into imsi_data values('10001',123456,10,165,add_months((sysdate-1),-1));
insert into imsi_data values('10001',123456,10,165,add_months((sysdate-2),-1));

select * from imsi_data

ACCOUNT IMSI    SEQNO   PACKAGE_ID  EVENT_DATE       

1   10001   123456    9      164       9/4/2015 4:17:06 AM  
2   10001   123456    9      164       9/3/2015 4:17:18 AM  
3   10001   123456    9      164       9/2/2015 4:18:16 AM  
4   10001   123456   10      165      10/4/2015 4:18:34 AM  
5   10001   123456   10      165      10/3/2015 4:23:23 AM  
6   10001   123456   10      165      10/2/2015 4:23:31 AM  

Expected output: I need to see the data in one row, getting the latest seq no details and lastusagedate( as Previous seqno(9) latest date)

ACCOUNT IMSI  SEQNO   PACKAGEID  LastUsageDate        CurrentUsageDate 

10001   123456 10       165     9/4/2015 4:17:06 AM    10/4/2015 4:18:34 AM

My sql is here:

select account,
       imsi,
       lastusage_date,
       current_date,
       package_id,
       seqno
from (
   select ce.package_id,
          ce.seqno,
          ce.account,
          ce.IMSI,
          lag(ce.event_date) over(partition by ce.IMSI, ce.seqno order by ce.IMSI, ce.event_date desc) lastusage_date,
          ce.event_date current_date,
          row_number() over(partition by ce.imsi, ce.seqno order by ce.event_date desc) rn
   from imsi_data ce
    where ce.account = '10001' and ce.seqno in (10, 09)
    group by ce.account, ce.seqno, ce.imsi, ce.event_date, ce.package_id)
where rn =1

This is getting lastusagedate as null. But i should get the previous seq max event_date can any one pls help me out:

Answer 1

You can try the following:

select
    ce.account,
    ce.IMSI,
    ce.seqno,
    ce.package_id,
    (
      select 
          max(prev_seq_date_ivw.event_date) ev_date 
        from 
          imsi_data prev_seq_date_ivw 
        where 
          prev_seq_date_ivw.seqno = (
            select 
                max(prev_seq_ivw.seqno) 
              from 
                imsi_data prev_seq_ivw 
              where 
                prev_seq_ivw.seqno < ce.seqno
          )
    ) last_usage_date,
    max(ce.event_date) current_usage_date
  from imsi_data ce
  where ce.account = '10001' and ce.seqno in (10, 09)
  group by     
    ce.account,
    ce.IMSI,
    ce.seqno,
    ce.package_id;