在SQL Server查詢中將聚合表與另一個表聯接

Question

我有2個表AfricanRatings和AfricanRatingsAVG 。 AfricanRatingsAVG是查詢的結果：

INSERT INTO AfricanRatingsAVG 
SELECT RecipeID, COUNT(*) AS Count, AVG(Rating) AS RatingAVG
FROM AfricanRatings
GROUP BY RecipeID

當對AfricanRatingsAVG進行新輸入時，此查詢工作正常，並且更新AfricanRatings 。

使用了GridView控件，並且來自AfricanRatingsAVG的數據在GridView中顯示得很好。 我的問題：我還想從第三個表獲得數據，AfricanRecipes也包含在同一GridView中。 我在JOIN之后嘗試了JOIN，但沒有結果。 嘗試的最后兩個JOINS是：

SelectCommand="SELECT * 
FROM (SELECT RecipeID, COUNT(*) AS Count, AVG(Rating) AS RatingAVG
FROM AfricanRatings
GROUP BY RecipeID  ) AS AfricanRatingsAVG
JOIN (SELECT AfricanRecipes.RecipeID, AfricanRecipes.Category, AfricanRecipes.Name, AfricanRecipes.Description
FROM AfricanRecipes
GROUP BY RecipeID  ) AS AfricanRecipes ON (AfricanRatingsAVG.RecipeID = AfricanRecipes.RecipeID)"

和

SelectCommand="SELECT * 
FROM (SELECT RecipeID, COUNT(*) AS Count, AVG(Rating) AS RatingAVG
FROM AfricanRatings
GROUP BY RecipeID  ) AS AfricanRatingsAVG
JOIN AfricanRecipes.RecipeID, AfricanRecipes.Category, AfricanRecipes.Name, AfricanRecipes.Description
FROM AfricanRecipes
GROUP BY RecipeID AS AfricanRecipes ON (AfricanRatingsAVG.RecipeID = AfricanRecipes.RecipeID)"

上面的第一個JOIN給出錯誤消息：在選擇列表中， AfricanRecipes.Category列無效，因為它既不包含在聚合函數中也不在GROUP BY子句中。

第二個JOIN給出錯誤消息：

'，'附近的語法不正確

我在上面的連接上嘗試了數十種變體，但是沒有運氣。 任何幫助，將不勝感激。

Answer 1

SELECT 
    AfricanRatingsAVG.*,
    AfricanRecipes.RecipeID, 
    AfricanRecipes.Category, 
    AfricanRecipes.Name, 
    AfricanRecipes.Description 
FROM (
    SELECT 
       RecipeID, 
       COUNT(*) AS RecipeCount, 
       AVG(Rating) AS RatingAVG 
    FROM AfricanRatings 
    GROUP BY RecipeID 
) AfricanRatingsAVG 
    JOIN AfricanRecipes
        ON AfricanRatingsAVG.RecipeID = AfricanRecipes.RecipeID