SQL Server：每个月为行，每年为列

Question

我试图按年份整齐地分离数据，我有以下查询来完成此操作，但是，日期列 (YYYYMM) 显示每年的每个月。因此，除了其各自年份的行之外，大多数行的每个年度列都是零。

SELECT      
    DATEFROMPARTS(YEAR(l.Date), MONTH(l.Date), 01) AS YYYYMM,
    SUM(CASE WHEN l.State ='UT' AND YEAR(l.Date) = '2018' THEN 1 ELSE 0 END) AS 'UT - 2018',
    SUM(CASE WHEN l.State ='UT' AND YEAR(l.Date) = '2019' THEN 1 ELSE 0 END) AS 'UT - 2019',
    SUM(CASE WHEN l.State ='UT' AND YEAR(l.Date) = '2020' THEN 1 ELSE 0 END) AS 'UT - 2020',
    SUM(CASE WHEN l.State ='AZ' AND YEAR(l.Date) = '2018' THEN 1 ELSE 0 END) AS 'AZ - 2018',
    SUM(CASE WHEN l.State  ='AZ' AND YEAR(l.Date) = '2019' THEN 1 ELSE 0 END) AS 'AZ - 2019',
    SUM(CASE WHEN l.State ='AZ' AND YEAR(l.Date) = '2020' THEN 1 ELSE 0 END) AS 'AZ - 2020',
    SUM(CASE WHEN l.State ='NV' AND YEAR(l.Date) = '2020' THEN 1 ELSE 0 END) AS 'NV - 2020'
FROM
    dbo.list AS l,
    dbo.StatusLogs AS sl
WHERE
    sl.ListId = l.Id
GROUP BY    
    DATEFROMPARTS(YEAR(l.Date), MONTH(l.Date), 01)
ORDER BY    
    DATEFROMPARTS(YEAR(l.Date), MONTH(l.Date), 01)

我想要做的是只有 12 行（每个月 1 行）。像这样：

MM       UT - 2018     ....     NV - 2020
Jan        10                     5
Feb        5                      8
...
Dec        6                      7

Answer 1

学习使用正确、明确、标准、可读的JOIN语法。

然后，解决方法是更改​​GROUP BY 和SELECT：

 SELECT MONTH(l.Date) AS month,
        SUM(CASE WHEN l.State ='UT' AND YEAR(l.Date) = 2018 THEN 1 ELSE 0 END) AS [UT - 2018],
        SUM(CASE WHEN l.State ='UT' AND YEAR(l.Date) = 2019 THEN 1 ELSE 0 END) AS [UT - 2019],
        SUM(CASE WHEN l.State ='UT' AND YEAR(l.Date) = 2020 THEN 1 ELSE 0 END) AS [UT - 2020],
        SUM(CASE WHEN l.State ='AZ' AND YEAR(l.Date) = 2018 THEN 1 ELSE 0 END) AS [AZ - 2018],
        SUM(CASE WHEN l.State  ='AZ' AND YEAR(l.Date) = 2019 THEN 1 ELSE 0 END) AS [AZ - 2019],
        SUM(CASE WHEN l.State ='AZ' AND YEAR(l.Date) = 2020 THEN 1 ELSE 0 END) AS [AZ - 2020],
        SUM(CASE WHEN l.State ='NV' AND YEAR(l.Date) = 2020 THEN 1 ELSE 0 END) AS [NV - 2020]
 FROM dbo.list l JOIN
      dbo.StatusLogs sl
      ON sl.ListId = l.Id
 GROUP BY MONTH(l.Date)
 ORDER BY MONTH(l.Date);

我还删除了一堆单引号。单引号应仅用于日期和字符串常量。 YEAR() 返回一个数字，所以比较应该是一个数字。列别名确实不需要转义，但如果您有不符合要求的名称，请使用方括号。单引号将列名与值混淆。