如何从SQL Server中的查询获取最大日期？

Question

How can I get Max date (latest date) from my query for each player?

Data from table:

Id  PlayerId    Username    DateCreated 
2   777         player1     2018-01-01 00:00:00.0000000 
3   778         player2     2018-05-05 00:00:00.0000000 
5   777         player1     2018-04-04 00:00:00.0000000 

So the result will be just one record for player1(max DateCreated) and one record for player2

IF (@pageNumber IS NOT NULL AND @pageSize IS NOT NULL)
BEGIN
    SET @minNumber = (@pageNumber - 1) * @pageSize;
    SET @maxNumber = @pageNumber * @pageSize;
    SET @sql = @sql + ' TOP(@maxNumber) ROW_NUMBER () OVER (ORDER BY ' + @orderBy +') AS [RowNumber], ';
END
ELSE
    SET @sql = @sql + ' ROW_NUMBER () OVER (ORDER BY ' + @orderBy + ') AS [RowNumber], ';

SET @sql = @sql + ' COUNT(*) OVER () AS [RecordCount],* FROM (SELECT [PlayerId], [Username], [DateCreated], [Response] FROM TABLE with (nolock) ';

Answer 1

You can replace the subquery by below one.

SELECT [PlayerId], MAX([DateCreated]) AS LastDate FROM TABLE with (nolock)
group by [PlayerId]

Answer 2

What you want is this:

    SELECT Id
          ,PlayerId
          ,Username
          ,DateCreated  
    FROM
          (
            SELECT Id
                  ,PlayerId
                  ,Username
                  ,DateCreated 
                  ,ROW_NUMBER() OVER (Partition By PlayerId Order By DateCreated DESC) AS FilterMostRecent
            FROM Players
            ) x
     WHERE FilterMostRecent = 1

I suggest you use SQLFiddle to help us helping you :)

Try the query and see if it is what you expect

http://sqlfiddle.com/#!18/af1ec/4/0

And please, only use dynamic SQL as a last resort

http://www.sommarskog.se/dynamic_sql.html

and really, really avoid (NOLOCK)

https://blogs.sentryone.com/aaronbertrand/bad-habits-nolock-everywhere/

unless you really know what you are doing.