什么SQL查询会给我出售房屋的百分比（％）？

Question

什么SQL查询会给出房屋销售价格的百分比（％），而不是每个房屋的价格：

“区域”，“构建类型”和“月份”？

表格是

{ Mls No, Build Type, Area code, List price, Sold price, Sold data }

但我只需要：

percentage (%) of houses  "sold price " over List price for each:
    "Area code ", "Build type" and "Month"

MLS No.   Area  List Price  Contract    Price Sold  Date Sold   Building Type
N1959472  N11   329500      20/09/2010  317000      13/11/2010  Semi-Detac 
N1990464  N11   339000      08/11/2010  340000      17/11/2010  Apt

Answer 1

您可以group by“每”字段，并使用聚合计算百分比，例如：

select  Area
,       Buildtype
,       Month
,       100.0 * sum(case when SoldPrice > ListPrice then 1 else 0 end) / count(*)
from    YourTable
group by
        Area
,       Buildtype
,       Month

如果没有Month列，但只有日期列，请将month替换为：

SQL Server:      datepart(month, SoldDate)
Oracle/MySQL:    extract(month from SoldDate)

Answer 2

您不需要JOIN或UNION，只需将CASE放入查询中，如下所示：

select Area
     , Build_type
     , extract(month from sold_date) as month
     , SUM(case when sold_price > list_price then 1.0 else 0 end)
      /count(*) as pct_sold
  FROM theTable
 GROUP BY Area
        , build_type
        , extract(month from sold_date)

Answer 3

没有列Month。您不需要join或union，google用于GROUP BY。