GROUP_CONCAT but with limits to get more than one row

Question

I am developing a small jumbled-words game for users on a PtokaX DC hub I manage. For this, I'm storing the list of words inside a MySQL table. Table schema is as follows:

CREATE TABLE `jumblewords` (
    `id` INT(10) UNSIGNED NOT NULL AUTO_INCREMENT,
    `word` CHAR(15) NOT NULL,
    PRIMARY KEY (`id`),
    UNIQUE INDEX `word` (`word`)
)
COMMENT='List of words to be used for jumble game.'
COLLATE='utf8_general_ci'
ENGINE=MyISAM;

Now, in the game-engine; I want to fetch 20 words as a string randomly. This I can achieve with a query similar to this:

SELECT GROUP_CONCAT(f.word SEPARATOR ', ' )
FROM ( SELECT j.word AS word
    FROM jumblewords j
    ORDER BY RAND()
    LIMIT 20) f

but I have to execute this statement everytime the list expires(all 20 words have been put before user).

Can I modify this query so that I can fetch more than one row with the results as generated from the query I have above?

Answer 1

Probably an easier way to solve this problem is by storing the random words in a temporary table and later extract the values. A stored procedure would be perfect for that.

DELIMITER //
DROP PROCEDURE IF EXISTS sp_jumblewords //
CREATE PROCEDURE sp_jumblewords(no_lines INT)
BEGIN

    DROP TABLE IF EXISTS tmp_jumblewords;
    CREATE TEMPORARY TABLE tmp_jumblewords (
        `word` VARCHAR(340) NOT NULL);

    REPEAT 
        INSERT INTO tmp_jumblewords 
        SELECT GROUP_CONCAT(f.word SEPARATOR ', ' )
        FROM ( SELECT j.word AS word
                FROM jumblewords j
            ORDER BY RAND()
                LIMIT 20) f;

        SET no_lines = no_lines - 1;
        UNTIL no_lines = 0
    END REPEAT;

    SELECT * FROM tmp_jumblewords;

END //
DELIMITER ;

CALL sp_jumblewords(20);