Hoe de eerste rij-formulier SQL-groepsquery te krijgen?

Je zou Row_Number() kunnen gebruiken.

select UserId, Date, StoreId from  (select row_number() over(partition
by UserId order by date) as RowNumber,   UserId, Date, StoreId from
Transactions  ) as View1 where  RowNumber = 1

http://sqlfiddle.com/#!6/e536a/7