Unacceptable NLS Parameters in SQL Functions

The following NLS parameters are not accepted in SQL functions except for NLSSORT:

NLS_LANGUAGE
NLS_TERRITORY
NLS_DATE_FORMAT

The NLS_DATE_FORMAT and NLS_TERRITORY_FORMAT parameters are not accepted as parameters because they can interfere with required format models. A date format must be specified if an NLS parameter is in a TO_CHAR or TO_DATE function. As a result, NLS_DATE_FORMAT and NLS_TERRITORY_FORMAT are not valid NLS parameters for the TO_CHAR or TO_DATE functions. If you specify NLS_DATE_FORMAT or NLS_TERRITORY_FORMAT in the TO_CHAR or TO_DATE function, then an error is returned.

NLS_LANGUAGE can interfere with the session value of NLS_DATE_LANGUAGE. If you specify NLS_LANGUAGE in the TO_CHAR function, for example, then its value is ignored if it differs from the session value of NLS_DATE_LANGUAGE.