在SQL Server中将不规则的varchar转换为日期时间

Question

I'm working on revamping a database right now, and all the datetime's are stored in varchar's formatted like so: DDMonYY hhmm (ex. 13Mar99 2032).

I don't have a lot of experience with SQL, as I only just finished my first year of college so I'm having a really hard time trying to get this to work so any help would be appreciated.

Answer 1

All you should need to do for your particular string is to get a colon in between the hour and minute values. Something like:

SELECT CAST(STUFF('13Mar99 2032', LEN('13Mar99 2032') - 1, 0, ':') AS datetime)

should work.

Answer 2

You can pick a datetime format and then shift parts of the string to match it. For example, format 7 is:

select  convert(varchar(25), getdate(), 7)
-->
'Jun 23, 14'

So you can use substring to transform your string:

declare @orig varchar(30) = '13Mar99 2032'
declare @conv varchar(30)

select  @conv = substring(@orig, 3, 3) + ' ' + substring(@orig, 1, 2) + ', ' +
    substring(@orig, 6, 2) + ' ' + substring(@orig, 9, 2) + ':' + substring(@orig, 11, 2)

select  @conv
,       convert(datetime, @conv, 7)
-->
'Mar 13, 99 20:32'          1999-03-13 20:32:00.000