Are you doing some datetime manipulation or maybe you are migrating from some database technology to MySQL or possibly using milliseconds?
Here is an example on how to go about it:

Say you have the following date: MAR 16 2008 09:12:51:893AM
SELECT DATE_FORMAT(STR_TO_DATE('MAR 16 2008 09:12:51:893AM','%M %d %Y %h:%i:%s:%f%p'),'%Y%m%d%k%i%s.%f'); --> 2008031691251.893000


What if its PM rather than AM
SELECT DATE_FORMAT(STR_TO_DATE('MAR 16 2008 09:12:51:893PM','%M %d %Y %h:%i:%s:%f%p'),'%Y%m%d%k%i%s.%f'); --> 20080316211251.893000


Ok so this is just simple string manipulation where:
%M is the month name
%d is day number
%Y is the year
%h is the hour
%i is the minute
%s is the second
%f is the microsecond
%p is the period: ante or post meridiem
In the DATE_FORMAT part we se a %k which is …

Once upon a time`stamp`, in a `data`base far far away, someone filed a bug named: `Microseconds precision is not retained by TIME, DATETIME, and TIMESTAMP field types.` – Bug Number 8523. This was the beginning of 2005, yet now that we are approaching the end of 2009, after 4.5 years, many (including myself) are still asking for this.

In fairness sake, MySQL have indeed supplied a way to retain milli and micro seconds in a decimal field `DECIMAL(17,3)`, and it is also queryable as if it were a timestamp BUT why isn’t it possible to store in a `DATETIME` or `TIMESTAMP` field? Why can’t we run a ’select now()’ or ’select curtime()’ etc and get a full timestamp including milli / micro seconds?

I have counted 37 different usernames asking for this feature, spanning from 15th Feb 2005 to recently. (list found below)

Some have suggested UDFs, others suggested using log4j while others, pretty annoyed, allegedly went …