MySQL Pass table name to cursor select - mysql

Question

I want the procedure to take parameter answertable and partid in the select statement,
but when i call it it doesn't replace the parameter answertable with the value
the call call updateTotalScores('quiz_participation', 'quiz_answer', 1)
returns the error: 1146 - Table 'quizdb.answertable' doesn't exist
passing the id works, but passing the table name doesn't
so how do i pass the table name to the select in
DECLARE cur1 CURSOR FOR SELECT SUM(`score`), SUM(`maxscore`) FROM answertable WHERE `idParticipation`=partid;
entire procedure:
DELIMITER $$
CREATE PROCEDURE updateTotalScores(IN participationtable CHAR(64), IN answertable CHAR(64), IN partid INT)
BEGIN
DECLARE done INTEGER DEFAULT 0;
DECLARE sscore INTEGER DEFAULT 0;
DECLARE smaxscore INTEGER DEFAULT 0;
DECLARE cur1 CURSOR FOR SELECT SUM(`score`), SUM(`maxscore`) FROM answertable WHERE `idParticipation`=partid;
DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = 1;
OPEN cur1;
REPEAT
FETCH cur1 INTO sscore, smaxscore;
UNTIL done = 1
END REPEAT;
CLOSE cur1;
UPDATE participationtable SET `score`=sscore, `maxscore`=smaxscore WHERE `idParticipation`=partid;
END $$
DELIMITER ;
For completeness
the table name cannot be passed to a MySql cursor, at least not yet
http://forge.mysql.com/worklog/task.php?id=3433
the answer from below (corrected a bit)
DELIMITER $$
CREATE PROCEDURE updateTotalScores(IN participation_table VARCHAR(45), IN answer_table VARCHAR(45), IN part_id INT)
BEGIN
SET #stmt_text=CONCAT("SELECT #score := SUM(`score`), #maxscore := SUM(`maxscore`) FROM ",
answer_table, " WHERE `idParticipation`=", part_id);
PREPARE stmt FROM #stmt_text;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;
SET #stmt_text=CONCAT("UPDATE ", participation_table,
" SET `score`=?, `maxscore`=? WHERE `idParticipation`=", part_id);
PREPARE stmt FROM #stmt_text;
EXECUTE stmt USING #score, #maxscore;
DEALLOCATE PREPARE stmt;
END $$

Answer 1

I believe you cannot do it in this manner.
In order to achieve this, you should use Dynamic SQL.
Note that you cannot open a cursor using Dynamic SQL either. But in your case, there seems to be no need for a cursor.
If i understand your code correctly, you can just use user variables and probably achieve what you are trying to do using 2 Dynamically prepared statements.
SET #stmt_text=CONCAT("SELECT #score = SUM(`score`), #maxscore=SUM(`maxscore`) FROM ",
answertable, "WHERE `idParticipation`= ", partid);
PREPARE stmt FROM #stmt_text;
EXECUTE stmt USING #a;
And then you update the values using the below statement
SET #stmt_text=CONCAT("UPDATE", participationtable, " SET `score`=#score,
`maxscore`=#maxscore WHERE `idParticipation`=", partid);
PREPARE stmt FROM #stmt_text;
EXECUTE stmt USING #a;
DEALLOCATE PREPARE stmt;
Note: Please check the syntax. I cannot test it to verify it exactly but i hope you get the idea.