ORACLE 9I 中的日期格式类型
Date and Time Datatypes
In pre-Oracle9i databases, the only date/time datatype available is DATE,
which stores the date and time. In Oracle9i, the TIMESTAMP and INTERVAL
datatypes have been added to enhance the storage and manipulation of date and
time data. There are six date/time datatypes that can be used for defining
columns in a table: