Re: Selecting multiple dates that are outside a specified time period

Question

Hi All,
I have the following dataset/table structure:
Order #     Customer ID     Order Date
4     10     14-Jan-09
3     10     25-Jul-08
2     10     20-Jul-08
1     10     15-Jul-08
What I'm trying to do is a tad complicated for my skillset. I want to be able to select a particular order date for each unique individual but I need to apply a rule that if each subsequent order date falls within 180 days of the previous order date, the date gets ignored until it reaches an order date that is more than 180 days so it captures that particular order along with the initial (minimum) order. So for the example above the first order date for Customer ID #10 is 15-jul-2008, each subsequent order (Order #'s 2 and 3) are within 180 days so they get ignored until Order #4 comes along which is exactly 183 days after the first order date so this goes beyond the 180 day time limit and the record needs to get included so I need a query that will essentially pull the following two records:
Order #     Customer ID     Order Date
1     10     15-Jul-08
4     10     14-Jan-09
Thanks,
Ed

Answer 1

This works for your sample data
SQL> with sample_data as (
  2    select 4 ord_no, 10 cust_no, to_date('14-Jan-2009', 'dd-mon-yyyy') dt
  3    from dual union all
  4    select 3, 10, to_date('25-Jul-2008', 'dd-mon-yyyy') from dual union all
  5    select 2, 10, to_date('20-Jul-2008', 'dd-mon-yyyy') from dual union all
  6    select 1, 10, to_date('15-Jul-2008', 'dd-mon-yyyy') from dual)
  7  select sd.* from sample_data sd
  8    join (select cust_no, min(dt) dt from sample_data
  9          group by cust_no) mo
10      on sd.cust_no = mo.cust_no and
11         (sd.dt = mo.dt or
12          sd.dt >= mo.dt + 180);
    ORD_NO    CUST_NO DT
         4         10 14-JAN-2009
         1         10 15-JUL-2008This will also include all orders more than 180 days after the first order.
John