mysql出现“Every derived table must have its own alias”

Every derived table must have its own alias

这句话的意思是说每个派生出来的表都必须有一个自己的别名

select name1 name, java, jdbc, hibernate,total
  from (select sc1.name name1, sc1.mark java
   from student_course2 sc1
   where sc1.course='java') as a,
   (select sc2.name name2, sc2.mark jdbc
   from student_course2 sc2
   where sc2.course='jdbc') as b,
   (select sc3.name name3, sc3.mark hibernate
   from student_course2 sc3
   where sc3.course='hibernate') as c,
 (select sc4.name name4,sum(sc4.mark) total
 from student_course2 sc4 group by sc4.name) as d
  where name1=name2 and name2=name3 and name3=name4 order by total ASC;