You can specify the character set of parameters that are defined
    as character data types. SQL assumes the character set of
    parameters based on the following rules:

    o  If a parameter is not qualified by a character set or defined
       as a national character data type, SQL considers the parameter
       to be of the default character set as specified in the DEFAULT
       CHARACTER SET clause.

    o  If a parameter is defined as a national character data type
       (NCHAR, NCHAR VARYING), SQL considers the parameter to be
       of the national character set as specified in the NATIONAL
       CHARACTER SET clause.

    o  If a parameter is defined as a data type qualified by a
       character set, SQL considers the parameter to be of that
       character set.

    See the Oracle Rdb SQL Reference Manual for information about
    data types and qualifying a data type with a character set.
    The Argument INTEGER topic describes the INTEGER data type with
    regard to the SQL module language.

    The SQL data type specified for the formal parameter in a module
    must be equivalent to the data type of the host language variable
    declaration for the actual parameter. If the formal parameter and
    actual parameter are not declared with equivalent data types, SQL
    can give unpredictable results.

    The data type for a database key is CHAR(n),  where n equals
    the number of bytes of the database key. See the Oracle Rdb SQL
    Reference Manual for more information on database keys.