For NLS-compliant applications, avoid hard-coding a string containing a month name. However, if a hard coded month name is essential, avoid using the COPY Built-in. If you use COPY, the month name may be incorrect, depending on which language is specified. (To specify a date in a library, use a variable for the date and COPY will work.)
Language-dependent example (not recommended):
:emp.hiredate := '30-DEC-96';
copy ('30-DEC-96','emp.hiredate');
Instead, use TO_DATE, as shown in the following example.
Language-independent example (recommended):
:emp.hiredate := to_date(30-12-1996,DD-MM-YYYY);