Mysql存储过程错误＃1064

Question

              SET @sql = NULL;

              SELECT 
                GROUP_CONCAT(DISTINCT
                              CONCAT('sum(case when week = ',week,
                                     'then totaltime else 00 end) AS `',
                                         week, '`')
                             )INTO @sql
                FROM   mytable;

                 SET @sql = CONCAT('SELECT TRIM(UPPER(mytable.empcode))AS CODE, 
                 TRIM(UPPER(mytable.empname)) EMPNAME,
                 ', @sql, ' 
                 from  mytable
                 group by empcode
                 order by empname ');
           PREPARE stmt FROM @sql;
           EXECUTE stmt;
           DEALLOCATE PREPARE stmt;
           END

我在这里使用数据透视表，想根据查询动态生成的周字段来计算总时间的总和，但是我收到了错误：

  

＆＃34;＃1064 - 您的SQL语法出错;检查手册   对应于您的MySQL服务器版本，以便使用正确的语法   通过empcode或＆＃39;来自mytable group附近的＆＃39;在第6行＆＃34;