Connector/Net 6.5 and higher support the fractional seconds feature introduced in MySQL 5.6.4. Fractional seconds could always be specified in a date literal or passed back and forth as parameters and return values, but the fractional part was always stripped off when stored in a table column. In MySQL 5.6.4 and higher, the fractional part is now preserved in data stored and retrieved through SQL. For fractional second handling in MySQL 5.6.4 and higher, see Fractional Seconds in Time Values. For the behavior of fractional seconds prior to MySQL 5.6.4, see Fractional Seconds in Time Values.

To use the more precise date and time types, specify a value from 1 to 6 when creating the table column, for example TIME(3) or DATETIME(6), representing the number of digits of precision after the decimal point. Specifying a precision of 0 leaves the fractional part out entirely. In your C# or Visual Basic code, refer to the Millisecond member to retrieve the fractional second value from the MySqlDateTime object returned by the GetMySqlDateTime function. The DateTime object returned by the GetDateTime function also contains the fractional value, but only the first 3 digits.

For related code examples, see the following blog post: https://blogs.oracle.com/MySqlOnWindows/entry/milliseconds_value_support_on_datetime