"I tried to export with format 'mm/dd/yyyy HH:mm:ss.SSS a', "
Months are MM, minutes are mm:
"How can I fix this?"
Use the correct format for months. But you have another problem:
in = '1/2/1900 13:13:21.897 AM';
dt = datetime(in, 'inputFormat','MM/dd/y HH:mm:ss.SSS a')
As the warning states, it is highly unusual to use 24 hour times with AM/PM, and causes unexpected outputs.
Perhaps you want this:
dt = datetime(regexprep(in,'\s*[AP]M$',''), 'inputFormat','MM/dd/y HH:mm:ss.SSS')
"How do I extract just the time from this column?"
Use TIMEOFDAY(): https://www.mathworks.com/help/matlab/ref/datetime.timeofday.html
t = timeofday(dt)
PS: Practice reading the documentation, you can find all date/time functions here:
