Question

我遇到自联接表的问题，其中group by工作不正常或我的代码出错。

我正在尝试制作一个表格，其中包含住房销售数据，我希望按地区和住房类型分组结果。

到目前为止，这是我所拥有的，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;

这给了我错误ORA-00979: not a GROUP BY expression。

当我遵循SQL规则，并且我将所有项目添加到group by子句时，我得到的结果类似于order by statement ....

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;

有人可以告诉我我做错了吗？？

Answer 1

注意： 根据其他信息进行编辑。还修复了原始答案中不匹配的括号。

请求的输出如下所示：

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

如果您需要一个组的总体百分比，唯一安全的方法是首先计算总“卖价”和总“卖价”，然后对总数进行计算。为此你需要一个子查询来总结一切。然后外部查询可以进行数学运算。

尝试这样的事情：

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

附录问题重申为“所售房屋的百分比超过要价，按地区划分”。

方法是计算（a）房屋数量和（b）以高于要价的价格销售的数量，以及按地区划分的数量。这是内部查询。它也按房屋类型转弯。外部查询计算百分比。这是：

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

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