将GETDATE()转换为指定日期格式的varchar类型

CREATE FUNCTION [dbo].[FormatDate]
(@date as datetime,
@formatstring as varchar(100)
)
RETURNS varchar(100) AS
BEGIN
declare @datestring as varchar(100)
set @datestring=@formatstring
--year
set @datestring=replace(@datestring, 'yyyy', cast(year(@date) as char(4)))
set @datestring=replace(@datestring, 'yy', right(cast(year(@date) as char(4)),2))
--millisecond
set @datestring=replace(@datestring, 'ms', replicate('',3-len(cast(datepart(ms,@date) as varchar(3)))) + cast(datepart(ms, @date) as varchar(3)))
--month
set @datestring=replace(@datestring, 'mm', replicate('',2-len(cast(month(@date) as varchar(2)))) + cast(month(@date) as varchar(2)))
set @datestring=replace(@datestring, 'm', cast(month(@date) as varchar(2)))
--day
set @datestring=replace(@datestring, 'dd', replicate('',2-len(cast(day(@date) as varchar(2)))) + cast(day(@date) as varchar(2)))
set @datestring=replace(@datestring, 'd',  cast(day(@date) as varchar(2)))
--hour
set @datestring=replace(@datestring, 'hh', replicate('',2-len(cast(datepart(hh,@date) as varchar(2)))) + cast(datepart(hh, @date) as varchar(2)))
set @datestring=replace(@datestring, 'h',  cast(datepart(hh, @date) as varchar(2)))
--minute
set @datestring=replace(@datestring, 'nn', replicate('',2-len(cast(datepart(n,@date) as varchar(2)))) + cast(datepart(n, @date) as varchar(2)))
set @datestring=replace(@datestring, 'n', cast(datepart(n, @date) as varchar(2)))
--second
set @datestring=replace(@datestring, 'ss', replicate('',2-len(cast(datepart(ss,@date) as varchar(2)))) + cast(datepart(ss, @date) as varchar(2)))
set @datestring=replace(@datestring, 's', cast(datepart(ss, @date) as varchar(2)))
return @datestring
END