根据月份值默认年份答案

【问题标题】：Default the year based on month value根据月份值默认年份
【发布时间】：2015-09-07 18:45:04
【问题描述】：

我有一个查询来显示表中的年份值并默认为当前年份。

select distinct year(startdate) as syear, year(startdate) as eyear, 1 as sOrder from [TTS].[dbo].[Class] where year(startdate) <> year(getdate())
    union all
    select year(getdate()) as syear, year(getdate()) as eyear, 0 as sOrder
    order by sOrder asc, syear desc

这里的默认年份是 2015 年（Sorder 0）。现在我需要根据月份值显示默认年份。例如，如果年份是 2015 年，月份是 1 月、2 月、3 月、4 月，则默认年份是 2015 年。否则默认年份是 2016 年。我尝试了以下查询

select distinct year(startdate) as syear, year(startdate) as eyear, 1 as sOrder  from [TTS].[dbo].[Class]  where
 year(startdate) <> year(getdate())
union all
select year(getdate())+1 as syear, year(getdate())+1 as eyear, 0 as sOrder where month(getdate()) not in(1,2,3,4) 
union all
select year(getdate()) as syear, year(getdate()) as eyear, 0 as sOrder where month(getdate())in(1,2,3,4)

order by sOrder asc, syear desc

但是年份值正在重复。有什么可以帮助我的吗？

【问题讨论】：

标签： sql sql-server

【解决方案1】：

SQL Server 的操作是正确的，因为您请求返回额外的行，如果现在运行 2015-06-22 将返回“2016” 您的 distinct 仅适用于您所做的第一个选择，因此这些是您的选择：

1) 将 cte 与 distincts 一起使用

with subq1 (syear, eyear, sOrder) as (select year(getdate())+1 as syear, year(getdate())+1 as eyear, 0 as sOrder where month(getdate()) not in(1,2,3,4) 
union all
select year(getdate()) as syear, year(getdate()) as eyear, 0 as sOrder where month(getdate())in(1,2,3,4)),
subq2 as (select distinct year(startdate) as syear, year(startdate) as eyear, 1 as sOrder  from [TTS].[dbo].[Class])

Select distinct syear, eyear, sOrder
from subq1
UNION ALL
select syear, eyear, sOrder
from subq2 s2
where s2.syear <> (select syear from subq1)

order by sOrder asc, syear desc

可以在此处找到用于此的 SQL Fiddle：http://sqlfiddle.com/#!6/f89b3a/3/0

2) 你可以尝试使用分组：

select distinct syear, eyear, min(sOrder)
from
(select distinct year(startdate) as syear, year(startdate) as eyear, 1 as sOrder 
from [TTS].[dbo].[Class]
union all
select year(getdate())+1 as syear, year(getdate())+1 as eyear, 0 as sOrder where month(getdate()) not in(1,2,3,4) 
union all
select year(getdate()) as syear, year(getdate()) as eyear, 0 as sOrder where month(getdate())in(1,2,3,4)) subq

Group by syear, eyear
order by min(sOrder) asc, syear desc

可以在此处找到用于此的 SQL Fiddle：http://sqlfiddle.com/#!6/f89b3a/5/0

我个人会推荐选项 1 而不是选项 2。

【讨论】：

我尝试了你的建议 1 。但我得到重复的结果。年订单 2016 2016 0 2016 2016 1 2014 2014 1 2013 2013 1 2012 2012 1 2011 2011 1 2010 2010 1 2009 2009 1 2008 2008 1 1900 190.在第二行中，需要 2015 年而不是 2016 年。有什么办法吗？
他们有不同的sOrder吗？
默认年份为0，否则为1
您的开始日期必须是 2016 年，这是导致问题的原因。
混合了我的表格，现在应该可以使用更新的表格了。

【解决方案2】：

您可以使用UNION 而不是UNION ALL 来排除重复项：

SELECT  YEAR(startdate) AS syear ,
        YEAR(startdate) AS eyear ,
        1 AS sOrder
FROM    [TTS].[dbo].[Class]
WHERE   YEAR(startdate) <> YEAR(GETDATE())
UNION
SELECT  YEAR(GETDATE()) + 1 AS syear ,
        YEAR(GETDATE()) + 1 AS eyear ,
        0 AS sOrder
WHERE   MONTH(GETDATE()) NOT IN ( 1, 2, 3, 4 )
UNION
SELECT  YEAR(GETDATE()) AS syear ,
        YEAR(GETDATE()) AS eyear ,
        0 AS sOrder
WHERE   MONTH(GETDATE()) IN ( 1, 2, 3, 4 )
ORDER BY sOrder ASC ,
        syear DESC

【讨论】：

【解决方案3】：

用下面的代码替换你的代码（你试图找到当前年份的地方）应该可以工作。

SELECT YEAR(DATEADD(MM,-4,GETDATE())) + 1

like 


SELECT DISTINCT year(startdate) AS syear
    ,year(startdate) AS eyear
    ,1 AS sOrder
FROM [TTS].[dbo].[Class]
WHERE year(startdate) <> year(getdate())

UNION ALL

SELECT YEAR(DATEADD(MM, - 4, GETDATE())) + 1 AS syear
    ,YEAR(DATEADD(MM, - 4, GETDATE())) + 1 AS eyear
    ,0 AS sOrder
ORDER BY sOrder ASC
    ,syear DESC

【讨论】：