如何按日期时间列排序并显示唯一的日期部分值？

Question

我在SQL Server 2012中有一个日期时间类型列。我想显示按该列升序排序的列的唯一日期部分。

我尝试了这个查询，但它按字符串类型排序。必须有一个简单的查询，但我想念它。

select distinct(convert(varchar, CreatedDate, 101)) from sometable order by 1

更新
我正在添加DDL语句。我认为这是一个简单的查询，快速简单的答案。

CREATE TABLE Test
(
    [CreatedDate] [datetime] NULL
) 

INSERT INTO [Test]([CreatedDate])  
VALUES(CAST('20161231 14:00:00.000' as DATETIME))
INSERT INTO [Test]([CreatedDate])  
VALUES(CAST('20170101 12:00:00.000' as DATETIME))
INSERT INTO [Test]([CreatedDate])
VALUES(CAST('20170101 11:00:00.000' as DATETIME))
INSERT INTO [Test]([CreatedDate])
VALUES(CAST('20170101 10:00:00.000' as DATETIME))
INSERT INTO [Test]([CreatedDate])
VALUES(CAST('20170201 03:00:00.000' as DATETIME))
INSERT INTO [Test]([CreatedDate])
VALUES(CAST('20160403 02:00:00.000' as DATETIME))

预期结果：

04/03/2016  
12/31/2016  
01/01/2017  
02/01/2017 

Answer 1

如果我没记错的话，你需要做这样的事情：

select convert(varchar, CreatedDate, 101)
from (
    select distinct convert(date, CreatedDate) as CreatedDate 
    from sometable
) X
order by CreatedDate

因为您无法按照您用于区别的不同字段进行排序。

Answer 2

将distinct更改为group by。这将允许您使用原始列进行排序：

<击>

<击>

SELECT CONVERT(char(10), CreateDate, 101)
FROM someTable
GROUP BY CONVERT(char(10), CreateDate, 101)
ORDER BY AVG(CreateDate)

<击>

感谢Juan Carlose Oropeza在rextester中创建演示 - 我想出了seems to be working fine：

的解决方案

SELECT CONVERT(char(10), CAST(CreatedDate as Date), 101)
FROM Test
GROUP BY CAST(CreatedDate as Date)
ORDER BY CAST(CreatedDate as Date)

Answer 3

如果问题是您按日期按字符串排序获得订单。

select distinct convert(varchar, CreatedDate, 101)
from sometable 
order by CreatedDate

Answer 4

为列创建别名，使用别名来排序。

选择         distinct（convert（varchar，CreatedDate，101））为OrderedDate     从某些人     订购OrderedDate

而不是不同，你可以使用group by来实现你想要的。

选择           将（varchar，CreatedDate，101）转换为OrderedDate    从某些人      Group By CreatedDate      按CreatedDate排序

以下代码按预期工作。经过测试。

select 
    convert(varchar,x.OrderedDate,101) 
from
(
 select 
    distinct cast(CreatedDate as date)  OrderedDate
 from 
 Test 
    ) x
 order by x.OrderedDate