Question

You have three fields ID, Date and Total. Your table contains multiple rows for the same day which is valid data however for reporting purpose you need to show only one row per day. The row with the highest ID per day should be returned the rest should be hidden from users (not returned).
To better picture the question below is sample data and sample output:

ID, Date, Total
1, 2011-12-22, 50
2, 2011-12-22, 150

The correct result is:

2, 2012-12-22, 150

The correct output is single row for 2011-12-22 date and this row was chosen because it has the highest ID (2>1)

Answer 1

Assuming that you have a database that supports window functions, and that the date column is indeed just date (and not datetime), then something like:

SELECT
    * --TODO - Pick columns
FROM
    (
       SELECT ID,[Date],Total,ROW_NUMBER() OVER (PARTITION BY [Date] ORDER BY ID desc) rn
       FROM [Table]
    ) t
WHERE
   rn = 1

Should produce one row per day – and the selected row for any given day is that with the highest ID value.