Oracle C++ Call Interface Programmer's Guide

External Datatypes
For byte 1, 119 represents the twentieth century, 1900 to 1999. A value of 120
would represent the twenty-first century, 2000 to 2099.
For byte 2, the second and third digits of the year are calculated as the year modulo
100. With a modulo division, the nonfractional portion is discarded:
1992 % 100 = 92
For byte 2, 192 represents the ninety-second year of the current century. A value of
100 would represent the zeroth year of the current century.
The year 2000 would yield 120 for byte 1 and 100 for byte 2.
For years prior to 0 CE, centuries and years are represented by the difference
between 100 and the number. So 01-JAN-4712 BCE is century 53 because 100 - 47 =
53. The year is 88 because the 100 - 12 = 88.
Valid dates begin at 01-JAN-4712 BCE. The month byte ranges from 1 to 31, the
hour byte ranges from 1 to 24, and the second byte ranges from 1 to 60.
When you enter a date in binary format by using the external datatype DATE, the
database does not perform consistency or range checking. All data in this format
must be validated before input.
When a DATE column is converted to a character string in your program, it is
returned in the default format mask for your session, or as specified in the
INIT.ORA file.
Note that this datatype is different from OCCI DATE which corresponds to a C++
Date datatype.
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Note: If no time is specified for a date, the time defaults to
midnight: 1, 1, 1.
Note: There is little need for the external datatype DATE. It is more
convenient to convert DATE values to a character format, because
most programs deal with dates in a character format, such as
DD-MON-YYYY. Instead, you may use the Date datatype.