Cumulative Game Score SQL I have developed a game recently and the database is running on MSSQL.

Here is my database structure

Table : Player

PlayerID uniqueIdentifier (PK)
PlayerName nvarchar


Table : GameResult

ID bigint (PK - Auto Increment)
PlayerID uniqueIdentifier (FK)
DateCreated Datetime
Score int
TimeTaken bigint
PuzzleID int


I have done an SQL listing Top 50 players that sort by highest score (DESC) and timetaken (ASC)
Sql below allowed me to get the result for each puzzle id. I'm not sure if it is 100% but I believe it is correct.

;with ResultSet (PlayerID, maxScore, minTime, playedDate) 
AS
(
  SELECT TOP 50 PlayerID, MAX(score) as maxScore, MIN(timetaken) as minTime, MIN(datecreated) as playedDate
    FROM gameresult
    WHERE puzzleID = @PuzzleID
    GROUP BY PlayerID
    ORDER BY maxScore desc, minTime asc, playedDate asc
)
SELECT RSP.[PlayerID], RSP.[PlayerName], RSA.maxScore, RSA.minTime, RSA.PlayedDate
FROM ResultSet RSA
INNER JOIN Player RSP WITH(NOLOCK) 
    ON RSA.PlayerID = RSP.PlayerID
ORDER BY 
    maxScore DESC, 
    minTime ASC,
    playedDate ASC


Question

1) I need to modify the SQL to do a cumulative rank of 3 puzzle ID. For example, Puzzle 1, 2, 3 and it should be sort by highest sum score (DESC), and sum timetaken (ASC)

2) I also need an overall score population for all the possible 1 to 7 puzzle.

3) Each player only allowed to appear on the list once. First played and first to get highest score will be rank 1st.

I tried using CTE with UNION but the SQL statement doesn't work.

I hope gurus here can help me out on this. Much appreciated.
Okay, so here is the query modified to work the way you want:

DECLARE @players table
(
    PlayerID uniqueidentifier NOT NULL PRIMARY KEY,
    PlayerName nvarchar(64) NOT NULL
);

DECLARE @playerScores table
(
    ID bigint NOT NULL IDENTITY PRIMARY KEY,
    PlayerID uniqueidentifier NOT NULL,
    DateCreated datetime NOT NULL,
    Score int NOT NULL,
    TimeTaken bigint NOT NULL,
    PuzzleID int NOT NULL
);

DECLARE @puzzleId int = 0;

SELECT TOP 50
    a.PlayerID,
    p.PlayerName,
    a.Score,
    a.TimeTaken,
    a.PlayedDate
    FROM
    (
        SELECT
            ps.PlayerID,
            ps.Score,
            ps.TimeTaken,
            ps.DateCreated AS PlayedDate,
            ROW_NUMBER()
                OVER
                (
                    PARTITION BY ps.PlayerID
                    ORDER BY ps.Score DESC, ps.TimeTaken, ps.DateCreated
                ) AS RN
            FROM @playerScores ps
            WHERE ps.PuzzleID = @puzzleId
    ) a
    INNER JOIN @players p ON p.PlayerID = a.PlayerID
    WHERE a.RN = 1
    ORDER BY
        a.Score DESC,
        a.TimeTaken,
        a.PlayedDate;


Having written this (note: indexes are not optimized), and looking at the other queries you're going to need to write, what I would actually recommend is to abandon this type of query entirely, and create a denormalized high-score table (rows are unique on the combination of PlayerID, PuzzleID), on which to run aggregates instead.

The reason why is because the GameResult table is going to grow huge in the database, and so it will be less and less efficient to run aggregates on it directly as time passes, and the requirements are incompatible with doing something like creating an indexed view to summarize the information.

Also, if you aren't doing this already, it's highly likely you'll want to use an asynchronous process to compute the "leaderboards" periodically and cache the results, instead of computing them just-in-time. (You could do something like merge the current player's score with the cached leaderboards so the player can see themself on the leaderboards immediately if they got a high score.) See my answer here for some ideas to consider when implementing a caching mechanism.