Combine date and time when date is a DateTime and time is a string

Question

I am working with an old mysql database in which a date is stored (without a time) as a datetime and a time is stored as a string (without a date).

In C# I then have a D

Answer 1

I think you're worrying about the string conversion too much. By combining the 2 string elements together you are saving further date string parsing anyway which will most likely be more expensive.

Is this going to be repeated a lot of times or a simple step in a larger process?