CREATE TABLE t (a TIMESTAMP(3) NOT NULL DEFAULT CURRENT_TIMESTAMP(0));

# Query OK, 0 rows affected (0.20 sec)

INSERT INTO t VALUES (NULL);

# Query OK, 1 row affected (0.04 sec)

SELECT * FROM t;

# +-------------------------+

# | a                       |

# +-------------------------+

# | 2012-08-07 04:18:48.353 |

# +-------------------------+

# 1 row in set (0.00 sec)

INSERT INTO t VALUES (CURRENT_TIMESTAMP(0));

# Query OK, 1 row affected (0.04 sec)

SELECT * FROM t;

# +-------------------------+

# | a                       |

# +-------------------------+

# | 2012-08-07 04:18:48.353 |

# | 2012-08-07 04:23:51.000 |

# +-------------------------+

# 2 rows in set (0.01 sec)