SQL Server 2012：将12小时AM / PM nchar转换为24小时DateTime格式

Question

First post/question here. I'm trying to convert an nchar to datetime. The examples I looked for all displayed converting to 12 hour from 24 or just dealing with time and not the full date with conversion. I'm not a native to SQL and I'm still learning the basics, so any help is appreciated.

I have a table with this format that I've read from a bulk insert of .txt files.

Alarm is nchar of text,

AlarmTime is also nchar of the date I read from the text file.

Alarm    |    AlarmTime
  1      |      7/6/2016 10:10:42 AM
  2      |      7/10/2016 6:41:23 PM
  3      |      8/4/2016 4:35:53 PM

I would like to get this into a datetime format and not be store as nchar. Whenever I try to convert I get an error: Conversion failed when converting date and/or time from character string.

The result I'm looking for is this just stored as datetime:

    Alarm    |    AlarmTime
      1      |      7/6/2016 10:10:42 
      2      |      7/10/2016 18:41:23 
      3      |      8/4/2016 16:35:53 

I have considered separating the date and time in to separate columns using a delimiter and then putting them both back together later. Or using the PM to add time then convert the colum to datetime. But those both seemed cumbersome, and I figured there was something easy I was missing to accomplish this.

Thanks in advance!

Answer 1

Since you are on 2012, I would suggest that you use Try_Convert(). This will trap any conversion errors. (Assuming your data string is m/d/y)

To identify the bogus records, try:

Select * from YourTable where Try_Convert(datetime,AlarmTime) is null

Sample Code to Reformat your data

Declare @YourTable table (Alarm int,AlarmTime nvarchar(50))
Insert Into @YourTable values
(  1,'7/6/2016 10:10:42 AM'),
(  2,'7/10/2016 6:41:23 PM'),
(  3,'8/4/2016 4:35:53 PM')

Select A.*
      ,ReFormated = format(try_convert(datetime,AlarmTime),'M/d/yyyy HH:mm:ss')
      ,AsDateTime = try_convert(datetime,AlarmTime)
 From  @YourTable A

Returns

Alarm   AlarmTime               ReFormated          AsDateTime
1       7/6/2016 10:10:42 AM    7/6/2016 10:10:42   2016-07-06 10:10:42.000
2       7/10/2016 6:41:23 PM    7/10/2016 18:41:23  2016-07-10 18:41:23.000
3       8/4/2016 4:35:53 PM     8/4/2016 16:35:53   2016-08-04 16:35:53.000