Question

对于Parking Citations的数据库，我编写了以下语法，以显示属于某些ViolFine参数的每个Citation的段：

SELECT Citation, Make, ViolCode, ViolDate, ViolFine
    ,CASE 
        WHEN ViolFine BETWEEN 0.00 AND 50.00 THEN '01. $0.00 - $50.00'
        WHEN ViolFine BETWEEN 50.01 AND 100.00 THEN '02. $50.01 - $100.00'
        WHEN ViolFine > 100 THEN '03. larger than $100.00'  
      END AS ViolFineSegments
FROM dbo.ParkingCitations
ORDER BY ViolDate DESC

现在我想获得GROUP上面定义的每个段的结果。我使用了以下内容，但似乎是将每个不同的ViolFine与相应的引用总数以及分段参数分组：

SELECT AVG(ViolFine) AS AvgFine, COUNT(Citation) AS NumberViolations
    ,CASE 
        WHEN AVG(ViolFine) BETWEEN 0.00 AND 50.00 THEN '01. $0.00 - $50.00'
        WHEN AVG(ViolFine) BETWEEN 50.01 AND 100.00 THEN '02. $50.01 - $100.00'
        WHEN AVG(ViolFine) > 100 THEN '03. larger than $100.00' 
      END AS ViolFineSegments
FROM dbo.ParkingCitations
GROUP BY  ViolFine
ORDER BY ViolFine

基本上，我希望每个组段只需要三行，显示平均引文和每个分组的计数，我确定如何继续。

我也尝试了下面的内容，但是只列出了一个长行，我想要三个单独的行。

SELECT COUNT(CASE WHEN ViolFine BETWEEN 0.00 AND 50.00 THEN '01. $0.00 - $50.00' END) '0-50',
       COUNT(CASE WHEN ViolFine BETWEEN 50.01 AND 100.00 THEN '02. $50.01 - $100.00' END) as '50-100',
       COUNT(CASE WHEN ViolFine > 100 THEN '03. larger than $100.00' END) as '>100',
       AVG(CASE WHEN ViolFine BETWEEN 0.00 AND 50.00 THEN ViolFine END) as '0-50',
       AVG(CASE WHEN ViolFine BETWEEN 50.01 AND 100.00 THEN ViolFine END) as '50-100',
       AVG(CASE WHEN ViolFine > 100 THEN ViolFine END) as '>100'
FROM dbo.ParkingCitations;

Answer 1

使用case表达式进行细分，并按该表达式分组，以获得平均值和计数。

SELECT 
CASE WHEN ViolFine BETWEEN 0.00 AND 50.00 THEN '01. $0.00 - $50.00'         
     WHEN ViolFine BETWEEN 50.01 AND 100.00 THEN '02. $50.01 - $100.00' 
     WHEN ViolFine > 100 THEN '03. larger than $100.00' 
END as fine_segment
,COUNT(*) as fine_count
,AVG(1.0*ViolFine) as avg_fine
FROM dbo.ParkingCitations
GROUP BY CASE WHEN ViolFine BETWEEN 0.00 AND 50.00 THEN '01. $0.00 - $50.00'         
              WHEN ViolFine BETWEEN 50.01 AND 100.00 THEN '02. $50.01 - $100.00' 
              WHEN ViolFine > 100 THEN '03. larger than $100.00' 
         END

Answer 2

我面前没有编辑器，但你可以在你拥有的每个案例陈述中使用UNION ALL

    SELECT AVG(ViolFine) AS AvgFine, COUNT(Citation) AS NumberViolations, AVG(ViolFine) AS [01. $0.00 - $50.00]
    FROM dbo.ParkingCitations
    GROUP BY  ViolFine
    HAVING AVG(ViolFine) BETWEEN 0.00 AND 50.00
    UNION ALL
    SELECT AVG(ViolFine) AS AvgFine, COUNT(Citation) AS NumberViolations, AVG(ViolFine) AS [02. $50.01 - $100.00]    
    ...

SQL - 为AVG和COUNT分组段

2 个答案: