How to retrieve microseconds or milliseconds from MySQL current time?

MySQL 5.6 supports the millisecond precision in the sysdate function.

try

select sysdate(6) will return 2013-04-16 13:47:56.273434

and

select sysdate(3) will return 2013-04-16 13:47:56.273


Take a look at what MySQL says(http://dev.mysql.com/doc/refman/5.1/en/fractional-seconds.html):

However, when MySQL stores a value into a column of any temporal data type, it discards any fractional part and does not store it.

So you need to store it not as a date value, but as a simple floating point value.