How to write a sql query to Sort or Group the dataset

Question

I have data in a table A as shown below. I want to group memberID as one set and sort the Date_Time in each set as shown in snapshot below

Date_Time        PersonID     Status
4/2/14 10:15 AM    ghi        Closed
4/1/14 9:15 AM     ghi        Cancelled
4/1/14 11:00 AM    abc        Cancelled
4/2/14 8:12 AM     def        Closed
4/1/14 9:17 AM     def        Hold
4/3/14 2:17 PM     abc        Hold
4/2/14 8:30 AM     abc        Open
4/3/14 8:16 AM     jkl        Closed
4/1/14 12:10 PM    jkl        Open
4/1/14 11:30 AM    abc        Hold

The final example-snapshot attached below you will see memberID: ghi first row date time ‘4/1/2014 9:15:00 AM’ is greater than memberID: def 1st row date_Time ‘4/1/2014 9:17:00 AM’ highlighted in yellow. And that is the main reason memberID ghi set tweaks as first set and then follows by memberID def set and then meberID abc, jkl … etc...

Could some one please help me how to write MS-SQL query to achieve the final result.

Thank you so much for your help.

Answer 1

If I'm understanding your question correctly, you need to join the table back to itself using the min aggregate to establish a sort order:

select t.*
from yourtable t
  join (
    select personid, 
      min(date_time) min_date_time
    from yourtable
    group by personid
    ) t2 on t.personid = t2.personid
order by t2.min_date_time, t.date_time

• SQL Fiddle Demo

Answer 2

Here's another way:

SELECT
  Date_Time,
  PersonID,
  Status
FROM
  dbo.atable
ORDER BY
  MIN(Date_Time) OVER (PARTITION BY PersonID),
  PersonID,
  Date_Time
;

The approach, though, is same as in sgeddes's answer, it just has different syntax. It calculates minimum Date_Time values using MIN(...) OVER (...). That makes a join to a derived table completely unnecessary.

One other little difference is that I have added PersonID to the ORDER BY clause to make sure that people with identical minimum Date_Time values do not have their rows mixed up.