An Error Was Encountered

Error Number: 1064

You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '' at line 4

select ((`1` * 1) + (`2` * 2) + (`3` * 3) + (`4` * 4) + (`5` * 5))/(`1` + `2` + `3` + `4` + `5`) as rate from rating where article_id =