user_defined_function

CREATE OR REPLACE FUNCTION fn_is_word_comprised(
    set_of_letters VARCHAR(50),
    word VARCHAR (50)
)
RETURNS BOOLEAN AS
$$
BEGIN
    RETURN TRIM(LOWER(word), LOWER(set_of_letters)) = '';
END
$$
LANGUAGE plpgsql;

-- SELECT fn_is_word_comprised('ois tmiah%f', 'halves');