如果列的特定值出现多次，如何检入SQL

Question

我正在尝试这个问题，我遇到了SUM特定区域的销售情况，然后需要根据名称stores创建另一个列，以便它可以判断该特定商店是否在该地区（东，西，北和南）。

我不知道从哪里开始 这些是两个表和输出：

Answer 1

SELECT r.Region_Name, SUM(s.Sales) Sales,
     CASE WHEN COUNT(g.Store_Name) > 0 THEN 'Y' ELSE 'N' END Stores
FROM (SELECT DISTINCT Region_name FROM Geography) r
LEFT JOIN Geography g ON g.Region_Name = r.Region_Name
LEFT JOIN Store_Information s ON s.Store_Name = g.Store_Name
GROUP BY r.Region_Name

Answer 2

注意：在你的问题中你没有提到数据库，所以我在SQL Server版本中添加了这个不适合MySQL的查询。我删除了问号[sql-server]。

这是您的代码（SQL Server版本）

SELECT GE.[RegionName] AS [Region_Name]
    ,ISNULL(SUM (SI.[NetSales]), 0) AS [NetSales]
    ,CASE WHEN SUM (SI.[NetSales]) IS NULL THEN N'N' ELSE N'Y' END AS [Stores]
FROM [DevDB].[dbo].[Geography] GE
LEFT JOIN (SELECT StoreName, SUM([Sales]) AS [NetSales]
    FROM [DevDB].[dbo].[Store_Information]
    GROUP BY StoreName) SI
ON SI.[StoreName] = GE.[StoreName]
GROUP BY GE.[RegionName]

<强>输出：

Answer 3

假设这是SQL Server，而Sales是NVARCHAR列。

SELECT DISTINCT 
        [Region_name], 
        ISNULL('$' + CAST(SUM(CAST(Sales as MONEY)) AS NVARCHAR(20)), '$0') Sales, 
        CASE WHEN SUM(CAST(Sales as MONEY)) > 0 
             THEN 'Y' 
             ELSE 'N' 
        END Stores 
FROM Geography geo
LEFT JOIN Store_Information sto ON sto.Store_Name = geo.Store_name
GROUP BY [Region_name]

Answer 4

在MYSQL中，您可以通过left join-ing store_info与geography表和group by列Region获得结果，如下所示。您不需要SUM再次单独CASE。

 SELECT g.region,
       sum(s.Sales) AS Sales,
       CASE
           WHEN Sales > 0 THEN 'Y'
           ELSE 'N'
       END AS Stores
FROM geography g
LEFT JOIN store_info s ON s.SN = g.SN
GROUP BY g.Region
ORDER BY 2 DESC

<强>结果

region  Sales   Stores
----------------------
West    2050    Y
East    700     Y
South   NULL    N
North   NULL    N

您可以查看演示here

希望这会有所帮助。