Creating an ID number based on date and time

I have a question that I think might be fairly simple to answer.
How to generate an identification number sequence using as a basis the date and time that is placed in the "Date of occurrence - Day and time" boxes. That is, the identification number is determined by the date and the sequence will be according to the dates and time that are placed in the "date of occurrence" and "Time" boxes.
For example:
Is this possible?

This is possible using concatenation, however, what would the ID number be if the Date and time of a second record is exactly the same which seems reasonable to me. Why not just use a one up scenario. Nothing more unique.

A2=sumproduct(($b$2:$b$99<>"")*($b$2:$b$99+$c$2:$c$99<b2+c2)*1)+1