How to write a SQL Server query to summarise table data? -

i need sql server query. have table this:

user_id     display_name          username              updated_on -------------------------------------------------------------------- 2012772                           user1.username        450958885 2012772     user1.displayname                           451124897 2155281                           user2.username        451045840 2162145                           user3.username        451147363 2162145     user3.displayname                           451147423 

and need output below: if display name user present render along updated_on else render username , updated on.

user_id     display_name_computed   updated_on ---------------------------------------------------- 2012772     user1.displayname       451124897 2155281     user2.username          451045840 2162145     user3.displayname       451147423 

the sql should select statement. no temp tables or table variables usage. no delete statements usage.

here go

select user_id   , coalesce(max(display_name), max(username)) display_name_computer   , max(updated_on) updated_on yourtable group user_id