in all honesty, if you are going to use 5 elements to build the date like this, i would use 5 fields in the database to store the date rather than trying to concatenate the 5 fields to one. this is just adding a layer of complexity to the insert and update process that is not needed.
with using the 5 fields, you can combine them to create a date using the STR_TO_DATE function in the recordsets where you displaythe date and or time:
http://dev.mysql.com/doc/refman/5.5/en/date-and-time-functions.html#function_str-to-date
