Mysql

在Mysql中两表联合查询时查询总条数。这个sql语句为什么不对：

select count(empolyee.id) from ( select *  from empolyee  join  departhment on empolyee.departhmentId = departhment.departhmentId       )  ，老是报Every derived table must have its own alias，请高手们指点