MySQL 5.6 and later supports microsecond precision in datetime.

You might want to branch it to include this only for 5.6, but
passing these values to < 5.6 doesn't cause issues either.
Test microsecond on mysql 5.6
Changelog entry for mysql56 microseconds
Merge pull request #14359 from arthurnn/mysql2_56_franc_sec

MySQL 5.6  Fractional Seconds