How does Oracle store the DATE datatype internally?

Question

SELECT EMP_NAME, SSN FROM EMP WHERE HIER_DATE = TO_DATE('03-NOV-1999','DD-MON-YYYY');

Answer 1

Oracle stores data in a proprietary format. It uses 7 bytes for Data storage and 1 byte is used for the length data.
The following is the mapping of the oracle's date type
Byte 1 -> Century
Byte 2 -> Year
Byte 3 -> Month
Byte 4 -> Day
Byte 5 -> Hour
Byte 6 -> Minute
Byte 7 -> Second