自發加入羣組？

Question

我有一個自加入表的問題，其中group by不能正常工作或者我的代碼有問題。

我正在嘗試生成一張表，其中包含住房銷售數據，並希望按地區和住房類型對結果進行分組。

這是我到目前爲止，它接近我所需要的。

SELECT A1.AREA AREA, 
    TRUNC((A1.SOLD_PRICE/A1.ASK_PRICE*100), 2) || '%' "ATT/ROW/TWNHOUSE", 
    TRUNC((A2.SOLD_PRICE/A2.ASK_PRICE*100), 2) || '%' "DETACHED", 
    TRUNC((A3.SOLD_PRICE/A3.ASK_PRICE*100), 2) || '%' "SEMI-DETACHED" 
FROM SALESRECORDS A1, SALESRECORDS A2, SALESRECORDS A3 
WHERE A1.AREA = A2.AREA AND A1.AREA = A3.AREA 
GROUP BY A1.AREA, A1.HOUSE_TYPE; 

這給了我錯誤ORA-00979: not a GROUP BY expression。

當我遵循SQL規則，我by子句中的所有項目添加到組，我得到類似於語句中的順序結果....

SELECT A1.AREA, 
    TRUNC((A1.SOLD_PRICE/A1.ASK_PRICE*100), 2) || '%' "ATT/ROW/TWNHOUSE", 
    TRUNC((A2.SOLD_PRICE/A2.ASK_PRICE*100), 2) || '%' "DETACHED", 
    TRUNC((A3.SOLD_PRICE/A3.ASK_PRICE*100), 2) || '%' "SEMI-DETACHED" 
FROM SALESRECORDS A1, SALESRECORDS A2, SALESRECORDS A3 
WHERE A1.AREA = A2.AREA AND A1.AREA = A3.AREA 
GROUP BY A1.AREA, A1.SOLD_PRICE, A1.ASK_PRICE, A2.SOLD_PRICE, A2.ASK_PRICE, 
    A3.SOLD_PRICE, A3.ASK_PRICE; 

誰能告訴我是什麼我做錯了....？

Answer 1

注意：根據附加信息編輯。還解決了我原始答案中不匹配的括號。

請求的輸出看起來是這樣的：

Area Att/Row/Twnhouse Detached Semi-Detached 
---- ---------------- -------- ------------- 
East 20.00%   33.33% 75.12% 
West 22.22%   44.44% 55.10% 

如果你需要爲一組的總百分比，唯一安全的方式做到這一點是計算總的「賣出價」總「問價格「，然後對總數進行數學計算。爲此你需要一個子查詢來總結一切。外部查詢可以進行數學運算。

嘗試這樣：

SELECT 
    Area "Area", 
    ROUND(TownhouseSold/TownhouseAsk * 100, 2) || '%' "Att/Row/Twnhouse", 
    ROUND(DetachedSold/DetachedAsk * 100, 2) || '%' "Detached", 
    ROUND(SemiDetachedSold/SemiDetachedAsk * 100, 2) || '%' "Semi-Detached" 
FROM (
    SELECT 
    Area, 
    SUM(CASE WHEN House_Type = 'Att/Row/Twnhouse' THEN Sold_Price END) AS TownhouseSold, 
    SUM(CASE WHEN House_Type = 'Att/Row/Twnhouse' THEN Ask_Price END) AS TownhouseAsk, 
    SUM(CASE WHEN House_Type = 'Detached' THEN Sold_Price END) AS DetachedSold, 
    SUM(CASE WHEN House_Type = 'Detached' THEN Ask_Price END) AS DetachedAsk, 
    SUM(CASE WHEN House_Type = 'Semi-Detached' THEN Sold_Price END) AS SemiDetachedSold, 
    SUM(CASE WHEN House_Type = 'Semi-Detached' THEN Ask_Price END) AS SemiDetachedAsk 
    FROM SalesRecords 
    GROUP BY Area 
) 
ORDER BY Area 

---

附錄問題重新表述爲「銷量比要價更高，由區住房的比例」。

方法是統計（a）房屋數量和（b）高於要價的銷售數量，並按面積分組。這是內部查詢。它也是房屋類型的樞紐。外部查詢計算百分比。這裏是：

SELECT 
    Area "Area", 
    ROUND(TownhouseOverAsk/TownhouseCount * 100, 2) || '%' "Att/Row/Twnhouse", 
    ROUND(DetachedOverAsk/DetachedCount * 100, 2) || '%' "Detached", 
    ROUND(SemiDetachedOverAsk/SemiDetachedCount * 100, 2) || '%' "Semi-Detached" 
FROM (
    SELECT 
    Area, 
    SUM(CASE WHEN House_Type = 'Att/Row/Twnhouse' THEN 1 END) AS TownhouseCount, 
    SUM(CASE WHEN House_Type = 'Att/Row/Twnhouse' AND Sold_Price > Ask_Price THEN 1 END) AS TownHouseOverAsk, 
    SUM(CASE WHEN House_Type = 'Detached' THEN 1 END) AS DetachedCount, 
    SUM(CASE WHEN House_Type = 'Detached' AND Sold_Price > Ask_Price THEN 1 END) AS DetachedOverAsk, 
    SUM(CASE WHEN House_Type = 'Semi-Detached' THEN 1 END) AS SemiDetachedCount, 
    SUM(CASE WHEN House_Type = 'Semi-Detached' AND Sold_Price > Ask_Price THEN 1 END) AS SemiDetachedOverAsk, 
    FROM SalesRecords 
    GROUP BY Area 
) 
ORDER BY Area