No module in the world is going to be able to extract a timestamp like that out from just a "YYYY-MM-DD" string (it certainly could make up something on the same day (usually midnight), but . . .). If you mean you've got a date field in a database, you're similarly up the creek since that would lack the requisite resolution as well.

Now if there's actually a datetime or timestamp (or whatever your DB calls it) value then you want to change how you're extracting the value from the database (and most likely would be able to get it returned to you in your desired format without need for further munging).

Not that that's a Perl problem, per se . . .