Storing dates in oracle

Question

Hi all,
Probably it might be a silly question, but it just made me wonder... how???
Here is my query....
It seems oracle stores dates in an internal numeric format, representing the century, year, month, day, hours, minutes and seconds. For example 07-Jun-1994 5:10:43 PM is stored in the database as
Century     Year     Month     Day     Hour     Minute     Second
19     94     06     07     5     10     43
The 19th century began on January 1, 1801 and ended on December 31, 1900. So the year 1994 has to be 20th century and not 19th century, but its confusing why it is stored in the database as 19th century.
Please let me know whether i am asking a correct question and please correct me if i am wrong.
-Satheesh

Answer 1

Satheesh_Kumar wrote:
Hi all,
Probably it might be a silly question, but it just made me wonder... how???
Here is my query....
It seems oracle stores dates in an internal numeric format, representing the century, year, month, day, hours, minutes and seconds. For example 07-Jun-1994 5:10:43 PM is stored in the database as
Century     Year     Month     Day     Hour     Minute     Second
19     94     06     07     5     10     43
The 19th century began on January 1, 1801 and ended on December 31, 1900. So the year 1994 has to be 20th century and not 19th century, but its confusing why it is stored in the database as 19th century.
Please let me know whether i am asking a correct question and please correct me if i am wrong.
-SatheeshNot exactly:
Century and year components are stored in 'excess 100 format', which means that 100 must be deducted from the byte's value. If a negative number results, then we've got a BC date at which point we take the absolute number. Also, to avoid ever having a zero byte, 1 is added to the hour, minute and second bytes. Therefore, 1 must be detected to get the correct value.
So 07-Jun-1994 5:10:43 PM is stored in the database as
Century     Year     Month     Day     Hour     Minute     Second
119     194     06     07     18     11     44SY.