Question

使用SQL Server 2012.我的视图有两个字段 - Machine Date和Total Mins。该视图仅显示上周的数据 - 这很好。然后我使用下面的SQL获得基于此视图的另一个视图：

SELECT        
    CASE WHEN DATENAME(dw, MachineMidLineDate) = 'Sunday' THEN [Total Mins] END AS Sun, 
    CASE WHEN DATENAME(dw, MachineMidLineDate) = 'Monday' THEN [Total Mins] END AS Mon, 
    CASE WHEN DATENAME(dw, MachineMidLineDate) = 'Tuesday' THEN [Total Mins] END AS Tues, 
    CASE WHEN DATENAME(dw, MachineMidLineDate) = 'Wednesday' THEN [Total Mins] END AS Wed, 
    CASE WHEN DATENAME(dw, MachineMidLineDate) = 'Thursday' THEN [Total Mins] END AS Thursday, 
    CASE WHEN DATENAME(dw, MachineMidLineDate) = 'Friday' THEN [Total Mins] END AS Friday, 
    CASE WHEN DATENAME(dw, MachineMidLineDate) = 'Saturday' THEN [Total Mins] END AS Sat
FROM
    dbo.vw_Machine_Minutes_Overview

然而，结果不是一行，它们随着每周的每一天而增加，即

Sun    Mon   Tues   Wed  Thurs  Fri   Sat
10     
       15
              25
                    20
                          21
                                12

但我需要将结果显示如下：

Sun    Mon   Tues   Wed  Thurs  Fri   Sat
10     15     25    20    21    12

我哪里错了？

Answer 1

您想要聚合：

SELECT SUM(CASE WHEN DATENAME(dw, MachineMidLineDate) = 'Sunday' THEN [Total Mins] END) AS Sun,
       SUM(CASE WHEN DATENAME(dw, MachineMidLineDate) = 'Monday' THEN [Total Mins] END) AS Mon,
      . . . 
FROM dbo.vw_Machine_Minutes_Overview;

Answer 2

关于使用pviot的评论是另一种方法：

工作示例： http://data.stackexchange.com/stackoverflow/revision/749735/930554/pivot-data-by-day-of-week-from-date-field

我发现语法有点令人困惑，但这应该有效：

select *
from 
(
select  datepart(dw,[MachineMidLineDate]) as DayOfWeek, [Total Mins]
  from #vw_Machine_Minutes_Overview 
) src
pivot
(
  sum([Total Mins])
  for DayOfWeek in ([1], [2], [3],[4],[5],[6],[7])
) piv;

datepart(dw,[MachineMidLineDate])部分返回1到7之间的数字，表示星期几，用于指定查询的[1],[2],[3]...部分中的列。

datepart：https://docs.microsoft.com/en-us/sql/t-sql/functions/datepart-transact-sql

pivot：https://technet.microsoft.com/en-us/library/ms177410(v=sql.105).aspx

SQL Group按星期几

2 个答案: