Convert string to DateTime without AM or PM otomatic addition

Your question is likely meaningless since it appears that a DateTime value is the number of 100-nanosecond intervals that have elapsed since 12:00:00 midnight, January 1, 0001. A DateTime value does not have the second or minute or hour or day or month or year or any conveniences such as that; those conveniences exist only when a DateTime value is converted to something else. So the answer to your question is that you need to convert the DateTime object to a string format that MySQL uses.