Your question is not clear. Your list shows that some computers had the records at 9 pm, do you mean that the time portion is wrong and you want to fix it ?
I think this does it:
update blah set col = dateadd(hour, -12, col)
where datepart( hour, col) > 12
It says that in table blah, update the column called col to be 12 hours less than what it currently is ( so, from 9 pm to 9 am, from 10 pm to 10 am, from 10 am to 10 pm the previous day ), where the hour portion of the date is greater than 12 ( so the last example I gave would not occur, only times past midday, get 12 hours removed ). You can change the logic a little further if you need to, to suit your circumstance.
Submit an article or tip