求一条sql,该如何处理

求一条sql

班级表(classes):班级id(id) ,班级名(class_name)

学生表(student):学生id(id),学生名(name),班级id(class_id)

要查:学生id,name,班级名,所在班级人数

 mysql 怎么写啊


SQL code

select 学生id,name,c.class_name,(select count(*) from student where class_id=s.class_id) as 所在班级人数
from student s ,classes c
where s.class_id=c.id


SQL code
select s.id,s.name,c.class_name,count(*)
from student s ,classes c
where s.class_id=c.id
group by s.id,s.name,c.class_name


select 学生id,name,c.class_name,(select count(*) from student where class_id=A.class_id) 
from student A INNER JOIN classes B ON A.class_id=B.id

SQL code
select a.id,a.name,b.class_name,(select count(*) from student where class_id=A.class_id)as'班级人数' 
from student a
left join classes b
on a.id=b.class_id;


                        
      
      
                    
求一条sql,该如何处理

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