sqlnzsql

how to group by a specific order?


eid start            end          status
6158963 11/27/2016  1/7/2017    FT
6158963 1/8/2017    5/9/2017    FT
6158963 5/10/2017   5/20/2017   LA
6158963 5/21/2017   7/31/2017   LA
6158963 8/1/2017    9/9/2017    FT
6158963 9/10/2017   10/21/2017  FT
6158963 10/22/2017  12/2/2017   FT
6158963 12/3/2017   12/16/2017  FT
6158963 12/17/2017  12/30/2017  FT
6158963 12/31/2017  3/3/2018    FT
6158963 3/4/2018    4/8/2018    FT

.

Above is the sample data which I am trying to convert. I am trying to convert the data based on the status.

The data should look like below :

eid start              end        status
6158963 11/27/2016  5/9/2017    FT
6158963 5/10/2017   7/31/2017   LA
6158963 8/1/2017    4/8/2018    FT

I am looking to group with the status field in the given order. but when I use max on the begin and end and group it by status. It just groups all the status into one.

eid MIN             MAX      status
6158963 11/27/2016  4/8/2018    FT
6158963 5/10/2017   7/31/2017   LA

Solution

  • You can use row_number() & do aggregation based on differences of sequence generated via row_number() :

    select eid, min(startdate) as startdate, max(endate) as endate, status
    from (select t.*,
                 row_number() over (partition by eid order by startdate) as seq1,
                 row_number() over (partition by eid, status order by startdate) as seq2
          from table t
         ) t
    group by eid, status, (seq1 - seq2)
    order by startdate;
    

    Assuming the startdate & enddates are in reasonable format.