sql - 以 varchar 格式选择不同的不同日期，并仅在月份和年份中显示/分组它们

Question

在我的一个数据库表中，有一列FinalDate将存储日期，数据类型不是datetimebut varchar。我想写一个查询，我可以选择 distinctFinalDate和 group/display like Jun 2012, Jul 2012.

该列的值FinalDate如下所示：

20120213  
20120225  
20120218  
20120306  
20120320

那么，我如何编写一个查询来选择不同的FinalDate并将它们显示在：

Feb 2012  
Mar 2012

Answer 1

Declare @a table (d varchar(8))
insert into @a Values ('20120213'),('20120225'),('20120218'),('20120306'),('20120320');


Select FinalDate
from
(
select Distinct 
 --DateName(Month,d)+' '+CAST(Datepart(yy,d) as Varchar(4)) as FinalDate
   SubString(DateName(Month,d),1,3)+' '+CAST(Datepart(yy,d) as Varchar(4)) as FinalDate
,Datepart(yy,d) as yy,Datepart(mm,d) as mm
from
(Select  CAST(d as datetime) as d from @a) a
) b
Order by yy,mm

Answer 2

试试这个——

询问：

DECLARE @temp TABLE (t VARCHAR(8))
INSERT INTO @temp VALUES 
    ('20120213'),
    ('20120225'),
    ('20120218'),
    ('20120306'),
    ('20120320')

SELECT LEFT(DATENAME(MONTH, t), 3) + ' ' + y
FROM (
    SELECT DISTINCT 
          t = CAST(LEFT(t, 6) + '01' AS DATETIME)
        , y = LEFT(t, 4)
    FROM @temp
) t
ORDER BY t

输出：

Feb 2012
Mar 2012

Answer 3

试试下面的查询

SELECT 
Count (SUBSTRING(CONVERT(char(12), CONVERT(date, StringDate,112),113),4,12)) as counts,
 SUBSTRING(CONVERT(char(12), CONVERT(date, StringDate,112),113),4,12) from Employees
 group by SUBSTRING(CONVERT(char(12), CONVERT(date, StringDate,112),113),4,12)

输出

counts  (No column name)
1   Apr 1992 
1   Aug 1992 
1   Jan 1994 
1   Mar 1994 
1   May 1992 
1   May 1993 
1   Nov 1994 
2   Oct 1993 

Answer 4

这是基于 CTE 的方法。将 [[[TABLE_NAME]]] 替换为包含 FinalDate 字段的表的实际名称。我在最终选择中而不是在 CTE 内部进行了处理，以防止 SQL Server 对过滤掉的（非序列 1）行执行处理。

WITH a AS (
    SELECT ROW_NUMBER() OVER (PARTITION BY LEFT(FinalDate, 6) ORDER BY FinalDate) seq, FinalDate 
    FROM [[[TABLE_NAME]]]
) SELECT LEFT(DATENAME(mm, FinalDate), 3) + ' ' + LEFT(FinalDate, 4)
FROM a
WHERE seq = 1