Mysqlで数値を単語に変換する

これはあなたを助けることができると思います...それはそれをするための単なる方法です：

DELIMITER $$
CREATE FUNCTION `number_to_string`(n INT) RETURNS varchar(100)
BEGIN
    -- This function returns the string representation of a number.
    -- It's just an example... I'll restrict it to hundreds, but
    -- it can be extended easily.
    -- The idea is: 
    --      For each digit you need a position,
    --      For each position, you assign a string
    declare ans varchar(100);
    declare dig1, dig2, dig3 int; -- (one variable per digit)

    set ans = '';

    set dig3 = floor(n / 100);
    set dig2 = floor(n / 10) - dig3*10;
    set dig1 = n - (dig3*100 + dig2*10);

    if dig3 > 0 then
        case
            when dig3=1 then set ans=concat(ans, 'one hundred');
            when dig3=2 then set ans=concat(ans, 'two hundred');
            when dig3=3 then set ans=concat(ans, 'three hundred');
            when dig3=4 then set ans=concat(ans, 'four hundred');
            when dig3=5 then set ans=concat(ans, 'five hundred');
            when dig3=6 then set ans=concat(ans, 'six hundred');
            when dig3=7 then set ans=concat(ans, 'seven hundred');
            when dig3=8 then set ans=concat(ans, 'eight hundred');
            when dig3=9 then set ans=concat(ans, 'nine hundred');
            else set ans = ans;
        end case;
    end if;

    if dig2 = 1 then
        case
            when (dig2*10 + dig1) = 10 then set ans=concat(ans,' ten');
            when (dig2*10 + dig1) = 11 then set ans=concat(ans,' eleven');
            when (dig2*10 + dig1) = 12 then set ans=concat(ans,' twelve');
            when (dig2*10 + dig1) = 13 then set ans=concat(ans,' thirteen');
            when (dig2*10 + dig1) = 14 then set ans=concat(ans,' fourteen');
            when (dig2*10 + dig1) = 15 then set ans=concat(ans,' fifteen');
            when (dig2*10 + dig1) = 16 then set ans=concat(ans,' sixteen');
            when (dig2*10 + dig1) = 17 then set ans=concat(ans,' seventeen');
            when (dig2*10 + dig1) = 18 then set ans=concat(ans,' eighteen');
            when (dig2*10 + dig1) = 19 then set ans=concat(ans,' nineteen');
            else set ans=ans;
        end case;
    else
        if dig2 > 0 then
            case
                when dig2=2 then set ans=concat(ans, ' twenty');
                when dig2=3 then set ans=concat(ans, ' thirty');
                when dig2=4 then set ans=concat(ans, ' fourty');
                when dig2=5 then set ans=concat(ans, ' fifty');
                when dig2=6 then set ans=concat(ans, ' sixty');
                when dig2=7 then set ans=concat(ans, ' seventy');
                when dig2=8 then set ans=concat(ans, ' eighty');
                when dig2=9 then set ans=concat(ans, ' ninety');
                else set ans=ans;
            end case;
        end if;
        if dig1 > 0 then
            case
                when dig1=1 then set ans=concat(ans, ' one');
                when dig1=2 then set ans=concat(ans, ' two');
                when dig1=3 then set ans=concat(ans, ' three');
                when dig1=4 then set ans=concat(ans, ' four');
                when dig1=5 then set ans=concat(ans, ' five');
                when dig1=6 then set ans=concat(ans, ' six');
                when dig1=7 then set ans=concat(ans, ' seven');
                when dig1=8 then set ans=concat(ans, ' eight');
                when dig1=9 then set ans=concat(ans, ' nine');
                else set ans=ans;
            end case;
        end if;
    end if;

    return trim(ans);
END$$

DELIMITER ;