Group by in T-SQL for selecting different columns

Question

I have following table ContactDetails . This table contains both cell phone as well as emails. These rows can be updated based on Users latest contact details. So userid (here 1) can have multiple rows grouped by Email and cell as below. There can be multiple users 2.3.4...so on

Rows are as below

   SrNo  Userid  ContactType  ContactDetail     LoadDate
    1    1       Email         x1.y@gmail.com   2013-01-01
    2    1       Cell          12345678         2013-01-01

    3    1       Email         x2.y@gmail.com   2012-01-01
    4    1       Cell          98765432         2012-01-01

    5    1       Email         x2.y@gmail.com   2011-01-01
    6    1       Cell          987654321        2011-01-01

I am looking for recent Email and Cell details of users. I tried running the query as below

Select 
   Userid, 
   Max(ContactDetail),
   MAX(LoadDate) 
from 
   ContactDetails 
group by 
   Userid, ContactType;

But I understand that this won't work.

Can anyone give some suggestion to pull the latest email and cell in single or sub-queries?

Cheers! Junni

Answer 1

You can use ROW_NUMBER() to select the most recent row of interest:

;With Ordered as (
    select UserId,ContactType,ContactDetail,LoadDate,
          ROW_NUMBER() OVER (
                PARTITION BY UserID,ContactType
                ORDER BY LoadDate DESC) as rn
    from ContactDetails
)
select * from Ordered where rn = 1