The LOWER function converts all uppercase characters in a value
    expression to lowercase characters. This function is useful to
    maintain consistency in value expressions in the database.

    If the result of the value expression is NULL, the function
    returns a null value.

    When you use the LOWER function, SQL follows the rules of
    the character set for the value expression when converting
    characters to lowercase. For example, if the character set of
    the value expression is Hanzi and ASCII, SQL converts only the
    ASCII characters to lowercase. It does not convert the Hanzi
    characters.