SQL：使用Null / Not Null条件编写3个参数的存储过程的更好（更短）方法？

Question

我有一个存储过程，它将有3个参数。我想检查Null / Not Null的每个组合，而不是用Else写出16个不同的Select语句如果条件我怎么能写它？这是我目前的例子......

...
    ELSE IF @team     IS NOT NULL AND
            @position IS NULL     AND
            @filter   IS NOT NULL

        BEGIN
            SELECT        P1.PlayerKey, P1.Player, P2.Position, P1.Height, P1.Weight, P1.Speed, P1.Status
            FROM          Player AS P1
            INNER JOIN    Position AS P2 ON P1.PositionID = P2.PositionID
            INNER JOIN    Team AS T1 ON T1.TeamID = P1.TeamID
            WHERE         P1.TeamID = @team AND P1.Player LIKE '%' + @filter + '%'
            ORDER BY      P2.PosSort;
        END

    ELSE IF @team     IS NULL     AND
            @position IS NOT NULL AND
            @filter   IS NOT NULL

        BEGIN
            SELECT        P1.PlayerKey, P1.Player, P2.Position, P1.Height, P1.Weight, P1.Speed, P1.Status
            FROM          Player AS P1
            INNER JOIN    Position AS P2 ON P1.PositionID = P2.PositionID
            INNER JOIN    Team AS T1 ON T1.TeamID = P1.TeamID
            WHERE         P2.Position = @position AND P1.Player LIKE '%' + @filter + '%'
            ORDER BY      P2.PosSort;
        END    

    ELSE IF @team     IS NOT NULL AND
            @position IS NULL     AND
            @filter   IS NOT NULL

        BEGIN
            SELECT        P1.PlayerKey, P1.Player, P2.Position, P1.Height, P1.Weight, P1.Speed, P1.Status
            FROM          Player AS P1
            INNER JOIN    Position AS P2 ON P1.PositionID = P2.PositionID
            INNER JOIN    Team AS T1 ON T1.TeamID = P1.TeamID
            WHERE         P1.TeamID = @team AND P1.Player LIKE '%' + @filter + '%'
            ORDER BY      P2.PosSort;
        END
...

Answer 1

SELECT
  P1.PlayerKey, P1.Player, P2.Position, P1.Height, P1.Weight, P1.Speed, P1.Status
FROM Player AS P1
INNER JOIN Position AS P2
  ON P1.PositionID = P2.PositionID
INNER JOIN Team AS T1
  ON T1.TeamID = P1.TeamID
WHERE (@team IS NULL OR P1.TeamID = @team)
AND (@filter IS NULL OR P1.Player LIKE '%' + @filter + '%')
AND (@position IS NULL OR P2.Position = @position)
ORDER BY P2.PosSort;