SQL组按不同时间段与日期

Question

我需要查询销售表,并让结果表显示给定日期内不同时间段的细分.

例如,该表包含以下字段:

Id (int), EntryDate (datetime), SaleReference (varchar) 

我想生成一个如下所示的表:

Date        Sales 9am-12pm   Sales 12pm-3pm   Sales 6pm-9pm
----------  --------------   --------------   -------------
01-01-2010        10               20               6  
02-01-2010        12               16               3  
03-01-2010        43               11               2  

任何有关这方面的帮助将不胜感激.谢谢

Answer 1

假设SQL Server在下面.如果不是类似的逻辑可能适用于您的RDBMS,但可能是一个不同的函数来从日期时间获取小时部分,BETWEEN的行为也可能不同(在SQL Server中它是一个包含范围).

SELECT CAST([Date] AS Date) AS [Date],
COUNT(CASE WHEN DATEPART(hour, [Date]) BETWEEN 9 AND 11 THEN 1 ELSE NULL END)
    AS [Sales 9am-12pm],
COUNT(CASE WHEN DATEPART(hour, [Date]) BETWEEN 12 AND 14 THEN 1 ELSE NULL END) 
    AS [Sales 12pm-3pm],
COUNT(CASE WHEN DATEPART(hour, [Date]) BETWEEN 18 AND 20 THEN 1 ELSE NULL END) 
    AS [Sales 6pm-9pm]
FROM Table
GROUP BY CAST([Date] AS Date) /*For SQL2008*/

注意:以前版本的SQL Server需要更多的环节来获取日期时间之外的日期部分.例如CAST(FLOOR( CAST( GETDATE() AS FLOAT ) ) AS DATETIME(从这里)