[sql]SELECT spalte1, spalte2
from hallo WHERE hour(spalte2) between 10 AND 12 AND spalte2 between "98-02 -03" AND "98-02 -04"
[/sql]
Ansonsten guck dir mal die Datumsfunktionen im Mysql-Handbuch an: http://dev.mysql.com/doc/mysql/en/Date_and_time_functions.html