sql - SQL Server 平均值/总和/组/计数查询问题

Question

我有下表：

╔══════════╦════════╦═══════╦═══════╗
║ PlayerID ║ GameID ║ Stat1 ║ Stat2 ║
╠══════════╬════════╬═══════╬═══════╣
║ 1 ║ A ║ 2 ║ 1 ║
║ 1 ║ B ║ 4 ║ 2 ║
║ 1 ║ C ║ 6 ║ 5 ║
║ 2 ║ A ║ 2 ║ 4 ║
║ 2 ║ B ║ 2 ║ 6 ║
║ 2 ║ C ║ 2 ║ 8 ║
║ 2 ║ D ║ 4 ║ 2 ║
║ 2 ║ E ║ 6 ║ 1 ║
║ 3 ║ A ║ 5 ║ 9 ║
║ 3 ║ G ║ 6 ║ 4 ║
║ 3 ║ 高 ║ 4 ║ 2 ║
║ 3 ║ N ║ 8 ║ 6 ║
╚══════════╩════════╩═══════╩═══════╝

我想要达到的目标如下：

╔══════════╦═══════════╦═══════════════════╦══════ ═════════════╗
║ PlayerID ║ GameCount ║ Stat 1 Avg / Game ║ Stat 2 Avg / Game ║
╠══════════╬═══════════╬═══════════════════╬══════ ═════════════╣
║ 1 ║ 3 ║ 4 ║ 2.66 ║
║ 2 ║ 5 ║ 3.2 ║ 4.2 ║
║ 3 ║ 4 ║ 5.75 ║ 5.25 ║
╚══════════╩═══════════╩═══════════════════╩══════ ═════════════╝

游戏计数应该是每个玩家玩的游戏总数，而统计数据应该是每场比赛的平均数。基本上 PlayerID 1 的计算如下：

“Stat1 平均 / 游戏” = (2 + 4 + 6) / 3 “Stat2 平均 / 游戏” = (1 + 2 + 5) / 3

我已经尝试了使用 SUMS 和 COUNTS 组合的同一查询的多种变体，但 GameCount 永远不会正确。我尝试过的一个例子如下

SELECT PlayerID, 
COUNT(GameID) AS GameCount, 
SUM(Stat1) / COUNT(GameID)  "Stat 1 Avg / Game",
SUM(Stat2) / COUNT(GameID)  "Stat 2 Avg / Game"
FROM PublishedStats A
GROUP BY PlayerID

SELECT PlayerID, 
COUNT(GameID) OVER (PARTITION BY PlayerID) AS GameCount, 
SUM(Stat1) /  COUNT(GameID) OVER (PARTITION BY PlayerID) "Stat 1 Avg / Game", 
SUM(Stat2) /  COUNT(GameID) OVER (PARTITION BY PlayerID) "Stat 2 Avg / Game", 
FROM Stats
GROUP BY PlayerID, GameID

Answer 1

所以只需添加 DISTINCT 关键字。

SELECT PlayerID, 
COUNT(DISTINCT GameID) AS GameCount, 
AVG(Stat1)  "Stat 1 Avg / Game",
AVG(Stat2)  "Stat 2 Avg / Game"
FROM PublishedStats A
GROUP BY PlayerID