x18845040365的博客

select student.id,student.name,book.stu_id ,count(*) as total from student, book wherestudent.id=book.stu_id and student.age=18 and student.gender=‘男’group by book.nameorder by total desc limit 1；面试时没看到book中id是否为主键的问题，如果为主键那么久不能有重复值，假设book的name是没有重复的，.