强制从SQL查询返回日期范围内的行数

Question

我正在对我们的SQL（2012）数据库运行查询，该查询返回给定日期范围内按日期分组的记录数。

例如：

Date Count 
12/08 12 
14/08 19 
19/08 11 

我需要填补空白为我绘制就会上当受骗，因为有遗漏值的图表。有没有办法强制SQL报告空白行，或者当它没有遇到结果时显示“0”值？

我的查询是

SELECT TheDate, count(recordID) 
FROM myTable 
WHERE (TheDate between '12-AUG-2013 00:00:00' and '20-AUG-2013 23:59:59') 
GROUP BY TheDate 

我需要创建一个临时表中的记录，然后从该选择并右键从myTable的加入任何记录？

感谢您的帮助！

Answer 1

如果您创建的日期范围的（临时或永久）表，然后你可以left join你的结果，以创建一个结果集包括空白

SELECT dates.TheDate, count(recordID) 
FROM 
(select 
     convert(date,dateadd(d,number,'2013-08-12')) as theDate 
    from master..spt_values 
    where type='p' and number < 9 
) dates 
left join yourtable on dates.thedate = convert(date,yourtable.thedate) 
GROUP BY dates.TheDate 

Answer 2

一个临时表可以完成这项工作，但是对于如此小的日期范围，您可以更简单一些，并使用一个UNION -ed子查询。例如：

SELECT dates.TheDate, ISNULL(counts.Records, 0) 
FROM 
(SELECT TheDate, count(recordID) AS Records 
FROM myTable 
WHERE (TheDate between '12-AUG-2013 00:00:00' and '20-AUG-2013 23:59:59') 
GROUP BY TheDate 
) counts 
RIGHT JOIN 
(SELECT CAST('12-AUG-2013' AS DATETIME) AS TheDate 
UNION ALL SELECT CAST('13-AUG-2013' AS DATETIME) AS TheDate 
UNION ALL SELECT CAST('14-AUG-2013' AS DATETIME) AS TheDate 
UNION ALL SELECT CAST('15-AUG-2013' AS DATETIME) AS TheDate 
UNION ALL SELECT CAST('16-AUG-2013' AS DATETIME) AS TheDate 
UNION ALL SELECT CAST('17-AUG-2013' AS DATETIME) AS TheDate 
UNION ALL SELECT CAST('18-AUG-2013' AS DATETIME) AS TheDate 
UNION ALL SELECT CAST('19-AUG-2013' AS DATETIME) AS TheDate 
UNION ALL SELECT CAST('20-AUG-2013' AS DATETIME) AS TheDate 
) dates 
ON counts.TheDate = dates.TheDate 

这是SQL Fiddle Demo。

如果您需要更通用（但也更复杂）的解决方案，请查看this excellent answer（by @RedFilter）以解决类似的问题。