You can use a quoted character string literal qualified by
    the name of a character set. The character string must contain
    characters only from the named character set.

    A string literal qualified by a character set begins with an
    underscore (_),  followed by the name of a supported character
    set, and a quoted string. No blank spaces are allowed outside of
    the literal.

    The following example shows how to qualify character strings with
    DEC_MCS and with DEC_KANJI:

    _DEC_MCS'Blue'

    _DEC_KANJI'Blue'

    You can use a national character string literal, which is a
    quoted character string literal qualified by the national
    character set. The character string must contain characters only
    from the national character set.

    A national character string literal begins with the letter N
    followed by a quoted string. No blank spaces are allowed outside
    of the literal.

    The following example shows how to qualify a character string
    with the national character set:

    N'Blue'