How to find the record in a table that contains the maximum value?

Question

Although this question looks simple, it is kind of tricky.

I have a table with the following columns:

table A:
  int ID
  float value
  datetime date         


        

Answer 1

As long as the Date column is unique for each group I think something like this might work:

SELECT A.ID, A.Value
FROM A
  INNER JOIN (SELECT Group, MAX(Date) As MaxDate FROM A GROUP BY Group) B
    ON A.Group = B.Group AND A.Date = B.MaxDate