Question

我的DateCompleted返回日期和时间。如果我想按日期分组并忽略时间。我该怎么做呢？

SELECT  
  Cast(Jobs.DateCompleted AS VarChar) AS 'DateCompleted',
  SUM(Metrics.GB) AS GB, 
  SUM(Metrics.KB) AS KB
FROM Metrics 
INNER JOIN Jobs ON Jobs.JobId = Metrics.JobId 
INNER JOIN Projects ON Projects.ProjectId = Jobs.ProjectId 
INNER JOIN JobTypes ON JobTypes.JobTypeId = Jobs.JobTypeId
WHERE Jobs.DateCompleted BETWEEN '12/01/2012' AND '12/03/2012' 
GROUP BY Jobs.DateCompleted

Answer 1

如果您使用的是SQL Server，那么您可以使用剥离时间的格式将值转换为varchar：

SELECT convert(char(10), Jobs.DateCompleted, 120) AS DateCompleted,
  SUM(Metrics.GB) AS GB, 
  SUM(Metrics.KB) AS KB
FROM Metrics 
INNER JOIN Jobs 
  ON Jobs.JobId = Metrics.JobId 
INNER JOIN Projects 
  ON Projects.ProjectId = Jobs.ProjectId 
INNER JOIN JobTypes 
  ON JobTypes.JobTypeId = Jobs.JobTypeId
WHERE Jobs.DateCompleted Between '12/01/2012' AND '12/03/2012' 
GROUP BY convert(char(10), Jobs.DateCompleted, 120)

如果您使用的是SQL Server 2008+，则可以将该值转换为日期：

SELECT cast(Jobs.DateCompleted as date) AS DateCompleted,
  SUM(Metrics.GB) AS GB, 
  SUM(Metrics.KB) AS KB
FROM Metrics 
INNER JOIN Jobs 
  ON Jobs.JobId = Metrics.JobId 
INNER JOIN Projects 
  ON Projects.ProjectId = Jobs.ProjectId 
INNER JOIN JobTypes 
  ON JobTypes.JobTypeId = Jobs.JobTypeId
WHERE Jobs.DateCompleted Between '12/01/2012' AND '12/03/2012' 
GROUP BY cast(Jobs.DateCompleted as date)

注意：我假设SQL Server基于您以前的标记

Answer 2

编写一个剥离时间部分的表达式，并按此表达式进行分组...在Ms SQL Server中，您可以使用DateAdd(dd, datediff(dd, 0, myDatetime), 0)每个RDBMS都有自己的函数或语法。对于Ms SQLServer，请参阅this SO question

Answer 3

答案是您将日期时间显式转换为日期（如果日期是受支持的数据类型）或隐式（转换为字符串）。

ANSI标准方法是执行以下操作：

select extract(year from jobs.DateCompleted),
       extract(month from jobs.DateCompleted),
       extract(day from jobs.DateCompleted),
. . .
group by extract(year from jobs.DateCompleted),
       extract(month from jobs.DateCompleted),
       extract(day from jobs.DateCompleted)

但是从来没有这样做过。在最新版本的SQL Server中，您将使用cast(jobs.DateCompleted as date)。在MySQL中，date(jobs.DateCompleted)。在Oracle中，我会to_char(jobs.DateCompleted, 'YYYY-MM-DD')。

Answer 4

你还没有指定rdbms，所以这是一个疯狂的猜测。

如果您使用的是SQL Server，则可以按日期时间的datepart分组。

GROUP BY DATEPART(year, Jobs.DateCompleted),
         DATEPART(month, Jobs.DateCompleted),
         DATEPART(day, Jobs.DateCompleted)

如何按日期分组，而不是时间因素？

4 个答案: