Question

当我尝试将字符集转换为日期格式时，我收到错误消息Conversion failed when converting date and/or time from character string我使用了以下查询，

SELECT TOP 1 FileName
    FROM #myFiles order by
    cast(
        (SUBSTRING(filename,23,4))+'-'+
        (SUBSTRING(filename,28,2))+'-'+
        (SUBSTRING(filename,30,2)) as date)
    desc

在以下记录中，

sfd_devtracker_back_2017_04_02_094339_4242105.bak
sfd_devtracker_back_2017_04_03_094339_4242105.bak
sfd_devtracker_back_2017_04_04_094339_4242105.bak

我在这里做错了什么？我的日期格式是否正确？

Answer 1

一种选择......

Declare @S varchar(max)='sfd_devtracker_back_2017_04_02_094339_4242105.bak'

Select try_convert(date,replace(substring(@S,charindex('_20',@S)+1,10),'_','-'))

返回

2017-04-02

表格

Declare @YourTable table (FileName varchar(max))
Insert Into @YourTable values
('sfd_devtracker_back_2017_04_02_094339_4242105.bak'),
('sfd_devtracker_back_2017_04_03_094339_4242105.bak'),
('sfd_devtracker_back_2017_04_04_094339_4242105.bak')

Select Top 1 *
 From  @YourTable
 Order By try_convert(date,replace(substring(FileName,charindex('_20',FileName)+1,10),'_','-')) Desc

返回

sfd_devtracker_back_2017_04_04_094339_4242105.bak

编辑实际上，无需转换为日期

Order By substring(FileName,charindex('_20',FileName)+1,10) Desc

Answer 2

你的数字有点偏差。这是另一种选择：


Warning: Source file 'foo.c' is newer than module file 'foo'.

如何在MS SQL Server中将字符集转换为日期格式

2 个答案: