求助大神 ~mysql存储过程，表名写成动态的怎么实现

Question

我写出来这样 执行不了，
DELIMITER $$

CREATE
/*[DEFINER = { user | CURRENT_USER }]*/
PROCEDURE db_test.total(IN tablename VARCHAR(45),OUT stotal INT)
/*LANGUAGE SQL
| [NOT] DETERMINISTIC
| { CONTAINS SQL | NO SQL | READS SQL DATA | MODIFIES SQL DATA }
| SQL SECURITY { DEFINER | INVOKER }
| COMMENT 'string'*/
BEGIN

SELECT COUNT(1) INTO stotal FROM tablename GROUP BY product_id;
END$$

DELIMITER ;
执行：
CALL total('n_z_gift_2016_11_04',@stotal)
错误提示：
Table 'db_test.tablename' doesn't exist

Answer 1

http://blog.csdn.net/ybhjx/article/details/50393420