SQL query concerning an account status

Question

Hello,
I have a table from which I wish to show on which date the account has entered the last serie of days on which it has been with status ST10. In the example the date we are looking for is 16.01.2009. The last time the account has shown such status (ST10) is from 16.01.2009 to 12.02.2009.
Below are the statements for the creation of the table and the insertion of records. Follow the link.
Thank you!
http://dox.bg/files/dw?a=5771159d36
Edited by: harkon on 2011-8-5 5:52

Answer 1

select max(repdate)
from ( select h.*,
nvl(h.repdate-lag(h.repdate) over (order by h.cust_ac_no, h.account_status, h.repdate)-decode(to_char(h.repdate,'DY'),'MON',2,0),100) date_diff
from harkon h
where h.cust_ac_no = '32AC7660106806191 '
and h.account_status = 'ST10 '
where date_diff > 1
or more understandable version:
select max(repdate)
from ( select h.*,
lag(h.repdate) over (order by h.cust_ac_no, h.account_status, h.repdate) prev_date,
decode(to_char(h.repdate,'DY'),
'MON',2,
0) weekend_correction
from harkon h
where h.cust_ac_no = '32AC7660106806191 '
and h.account_status = 'ST10 '
where nvl(repdate-prev_date-weekend_correction,100) > 1
Just to explain what I did:
First, I found out the previous date by using analytic function lag. I also found out the day (is it Monday, Tuesday, Wednesday...), because we have to do the correction if the current day is Monday, since we have 2 days (Saturday and Sunday) for which you do not have records in your table.
After that I found out what is the number of days between previous and current date, also using in account the correction for weekends, so that I can get the difference between Monday and previous Friday as 1 day. If the date has more than 1 day difference in regard to the previous date, it is our candidate for the starting date of the period. As long as the difference of dates is 1 the date is part of the period.
Than I selected maximum of these days, which is the last date when the change you are looking for happened.
Edited by: user13645481 on Aug 5, 2011 6:32 AM