T-SQL: 15 个与日期时间相关的精典语句函数

T-SQL: 15 个与日期时间相关的自定义函数(UDF),周日作为周的最后一天,均不受 @@DateFirst、语言版本影响
都是从老文章里收集或提炼出来的!
提示:
(@@Datefirst + datepart(weekday,@Date)) % 7 判断周几是最保险的! 与 @@DateFirst 无关,与语言版本无关
@@DateFirst 可能会导致 datepart(weekday,@Date) 不一样!
无论 @@DateFirst 等于几,无论是什么语言版本的 SQL Server 下面永远恒成立!@@Datefirst + datepart(weekday,@Date)): 2、3、4、5、6、0、1 分别代表 周一 到 周日
-- */
create function udf_GetAge(@StartDate datetime,@EndDate datetime)
returns integer
-- 返回精确年龄 select dbo.udf_GetAge('1949-10-01',getdate())
begin
return datediff(year,@StartDate,@EndDate)
- case when datediff(day,dateadd(year,datediff(year,@StartDate,@EndDate),@StartDate),@EndDate) >= 0
then 0
else
1
end
end
go

create function udf_DaysOfYearByDate(@Date datetime)
RETURNS integer
-- 返回年的天数 可判断 平(365)、润(366) 年
begin
return datediff(day,dateadd(year,datediff(year,0,@Date),0),dateadd(year,datediff(year,0,@Date )+1,0))
end
go
create function udf_DaysOfYear(@Year integer)
RETURNS integer
-- 返回年的天数 可判断 平(365)、润(366) 年
begin
return datediff(day,dateadd(year,@year - year(0),0),dateadd(year,@year - year(0) + 1,0))
end
go

create function udf_HalfDay(@Date datetime)
returns datetime
-- 返回 @Date 是 上午 返回 @Date 的零点,@Date 是 下午 返回 @Date 的十二点
as
begin
return case when datepart(hour,@Date)
go
create function udf_WeekDiff(@StartDate datetime,@EndDate datetime)
returns integer
-- 返回 [@StartDate , @EndDate] 之间周数 周日是当周的最后一天
begin
return datediff(week,@StartDate,@EndDate) -- + 1
+ case when (@@Datefirst + datepart(weekday,@StartDate)) % 7 = 1
then 1
else
0
end
- case when (@@Datefirst + datepart(weekday,@EndDate)) % 7 = 1
then 1
else 0
end
end
go

create function udf_WeekOfMonth(@Date datetime)
-- 返回 @Date 是所在月的第几周 周日是当周的最后一天
returns integer
as
begin
return datediff(week
,case when (@@Datefirst + datepart(weekday,dateadd(month,datediff(month,0,@Date),0))) % 7 = 1
then dateadd(month,datediff(month,0,@Date),0) - 1
else
dateadd(month,datediff(month,0,@Date),0)
end
,case when (@@Datefirst + datepart(weekday,@Date)) % 7 = 1
then @Date-1
else @Date
end
) + 1
end
go

create function udf_WeekOfQuarter(@Date datetime)
-- 返回 @Date 是所在季度的第几周 周日是当周的最后一天
returns int
as
begin
return datediff(week
,case when (@@Datefirst + datepart(weekday,dateadd(Quarter,datediff(Quarter,0,@Date),0))) % 7 = 1
then dateadd(Quarter,datediff(Quarter,0,@Date),0) - 1
else
dateadd(Quarter,datediff(Quarter,0,@Date),0)
end
,case when (@@Datefirst + datepart(weekday,@Date)) % 7 = 1
then @Date - 1
else
@Date
end
) + 1
end
go

create function udf_WeekOfYear(@Date datetime)
-- 返回 @Date 是所在年的第几周 周日是当周的最后一天
returns int
as
begin
return datediff(week
,case when (@@Datefirst + datepart(weekday,dateadd(day,0,datediff(day,0,dateadd(year,datediff(year,0,@Date),0))))) % 7 = 1
then dateadd(day,-1,dateadd(day,0,datediff(day,0,dateadd(year,datediff(year,0,@Date),0))))
else
dateadd(day,0,datediff(day,0,dateadd(year,datediff(year,0,@Date),0))) --date 所在年的第一天 即: 一月一号
end
,case when (@@Datefirst + datepart(weekday,@Date)) % 7 = 1
then dateadd(day,-1,@Date)
else
@Date
end
) + 1
end
go

create function udf_WeekDay(@ int,@Date datetime)
returns datetime
-- 返回 @Date 映射到 所在周的其他天 周日是当周的最后一天
begin
/*
--周日算作(上一)周的最后一天
当 @ = 7 代表将 @Date 映射到 所在周的星期日
可用于按周汇总 Group by,均支持跨年跨月数据
*/
return dateadd(day
,case when (@@Datefirst + datepart(weekday,@Date)) % 7 = 0 --周六
then case when @ between 1 and 6
then @ - 6
else
1
end
when (@@Datefirst + datepart(weekday,@Date)) % 7 = 1 --周日(七)
then case when @ between 1 and 6
then @ - 7
else
0
end
when (@@Datefirst + datepart(weekday,@Date)) % 7 between 2 and 6 --周一至周五
then case when @ between 1 and 6
then @ + 1 - (@@Datefirst + datepart(weekday,@Date)) % 7
else
8 - (@@Datefirst + datepart(weekday,@Date)) % 7
end
end
,@Date)
end
go

create function udf_WeekdayDiff(@Weekday integer,@StartDate datetime,@EndDate datetime)
returns integer
-- -- 返回 [@StartDate , @EndDate] 之间周一 到 周日的个数 周日是当周的最后一天
begin
-- @Weekday: 1: Monday , ... ,7: Sunday
return datediff(week,@StartDate,@EndDate)
+ case when (@@Datefirst + datepart(weekday,@StartDate)) % 7
+ case when (@@Datefirst + datepart(weekday,@StartDate)) % 7 = 0
then 7
else
0
end > @Weekday % 7 + 1
then 0
else 1
end
- case when (@@Datefirst + datepart(weekday,@EndDate)) % 7
+ case when (@@Datefirst + datepart(weekday,@EndDate)) % 7 = 0
then 7
else 0
end >= @Weekday % 7 + 1
then
0
else
1
end
/* test:
declare @b datetime
declare @e datetime
set @b = '2004-01-29'
set @e = '2004-09-05'
select @b as BeginDate ,@e as EndDate
,dbo.udf_WeekdayDiff(1,@b,@e) as CountOfMonday
,dbo.udf_WeekdayDiff(2,@b,@e) as CountOfTuesday
,dbo.udf_WeekdayDiff(3,@b,@e) as CountOfWednesday
,dbo.udf_WeekdayDiff(4,@b,@e) as CountOfThursday
,dbo.udf_WeekdayDiff(5,@b,@e) as CountOfFriday
,dbo.udf_WeekdayDiff(6,@b,@e) as CountOfSaturday
,dbo.udf_WeekdayDiff(7,@b,@e) as CountOfSunday
*/
end
go

create function udf_WeekdayID(@Date datetime)
returns integer
-- 返回 @Date 是 Monday 返回 1, ... ,是 Sunday 返回 1
begin
--1: Monday , ... ,7: Sunday
return (@@Datefirst + datepart(weekday,@Date)) % 7
+ case when (@@Datefirst + datepart(weekday,@Date)) % 7
go

create function udf_NextWorkDate(@Date datetime)
returns datetime
-- 返回 @Date 的下一个工作日
begin
/*
declare @i int
set @i = 3
declare @Date datetime
set @Date = '2005-01-02'
-- */
return case when (@@Datefirst + datepart(weekday,@Date)) % 7 = 6 -- Friday
then dateadd(day,3,@Date)
when (@@Datefirst + datepart(weekday,@Date)) % 7 = 0 -- saturday
then dateadd(day,2,@Date)
else
dateadd(day,1,@Date)
end
end
go

(

create function udf_PreviousWorkDate(@Date datetime)
returns datetime
-- 返回 @Date 的上一个工作日
begin
/*
declare @i int
set @i = 3
declare @Date datetime
set @Date = '2005-01-02'
-- */
return case when (@@Datefirst + datepart(weekday,@Date)) % 7 = 2 -- Monday
then dateadd(day,-3,@Date)
when (@@Datefirst + datepart(weekday,@Date)) % 7 = 1 -- Sunday
then dateadd(day,-2,@Date)
else
dateadd(day,-1,@Date)
end
end
go

create function udf_WorkDateAdd(@i integer,@Date datetime)
returns datetime
-- 返回 @Date 加上一段 @i 个工作日的新值
begin
declare @ int
set @ = 0
while @ = 0
then --dbo.udf_nextworkdate(@Date)
case when (@@Datefirst + datepart(weekday,@Date)) % 7 = 6 -- Friday
then dateadd(day,3,@Date)
when (@@Datefirst + datepart(weekday,@Date)) % 7 = 0 -- saturday
then dateadd(day,2,@Date)
else
dateadd(day,1,@Date)
end
else
--dbo.udf_previousworkdate(@Date)
case when (@@Datefirst + datepart(weekday,@Date)) % 7 = 2 -- Monday
then dateadd(day,-3,@Date)
when (@@Datefirst + datepart(weekday,@Date)) % 7 = 1 -- Sunday
then dateadd(day,-2,@Date)
else
dateadd(day,-1,@Date)
end
end
set @ = @ + 1
end
return @Date
end
go

create function udf_GetStar (@ datetime)
RETURNS varchar(100)
-- 返回日期所属星座
BEGIN
RETURN
(
--declare @ datetime
--set @ = getdate()
select max(star)
from
(
select '魔羯座' as star,1 as [month],1 as [day]
union all select '水瓶座',1,20
union all select '双鱼座',2,19
union all select '牡羊座',3,21
union all select '金牛座',4,20
union all select '双子座',5,21
union all select '巨蟹座',6,22
union all select '狮子座',7,23
union all select '处女座',8,23
union all select '天秤座',9,23
union all select '天蝎座',10,24
union all select '射手座',11,22
union all select '魔羯座',12,22
) stars
where dateadd(month,[month] - 1,dateadd(year,year(@) - year(0),0)) + [day] - 1 =
(
select max(dateadd(month,[month] - 1,dateadd(year,year(@) - year(0),0)) + [day] - 1)
from (
select '魔羯座' as star,1 as [month],1 as [day]
union all select '水瓶座',1,20
union all select '双鱼座',2,19
union all select '牡羊座',3,21
union all select '金牛座',4,20
union all select '双子座',5,21
union all select '巨蟹座',6,22
union all select '狮子座',7,23
union all select '处女座',8,23
union all select '天秤座',9,23
union all select '天蝎座',10,24
union all select '射手座',11,22
union all select '魔羯座',12,22
) stars
where @ >= dateadd(month,[month] - 1,dateadd(year,year(@) - year(0),0)) + [day] - 1
)
)
end

SQL Server 日期算法

一周的第一天
select @@DATEFIRST

一个月的第一天
select dateadd(mm,datediff(mm,0,getdate()),0)

本周的星期一
select dateadd(wk,datediff(wk,0,getdate()),0)

一年的第一天
SELECT DATEADD(yy, DATEDIFF(yy,0,getdate()), 0)

季度的第一天
SELECT DATEADD(qq, DATEDIFF(qq,0,getdate()), 0)

当天的零时
SELECT DATEADD(dd, DATEDIFF(dd,0,getdate()), 0)

上个月的最后一天 ：本月第一天减2ms.
SELECT dateadd(ms,-2,DATEADD(mm, DATEDIFF(mm,0,getdate()), 0))

本月的最后一天
SELECT dateadd(ms,-2,DATEADD(mm, DATEDIFF(m,0,getdate())+1, 0))

本月的第一个星期一

去掉时分秒
DATEADD(day, DATEDIFF(day,0,getdate()), 0)
显示星期几
select datename(weekday,getdate())
如何取得某个月的天数
SELECT Day(dateadd(ms,-3,DATEADD(mm, DATEDIFF(m,0,getdate())+1, 0)))

判断是否闰年：
SELECT case day(dateadd(mm, 2, dateadd(ms,-3,DATEADD(yy, DATEDIFF(yy,0,getdate()), 0))))
when 28 then '平年' else '闰年' end
一个季度多少天
declare @m tinyint,@time smalldatetime
select @m=month(getdate())
select @m=case when @m between 1 and 3 then 1
when @m between 4 and 6 then 4
when @m between 7 and 9 then 7
else 10 end
select @time=datename(year,getdate())+'-'+convert(varchar(10),@m)+'-01'
select datediff(day,@time,dateadd(mm,3,@time))