Mysql中表student_table(id,name,birth,sex)，插入如下记录：
('1004' , '张三' , '2000-08-06' , '男');
('1005' , NULL , '2001-12-01' , '女');
('1005' , NULL , '2001-12-01' , '女');
('1006' , '张三' , '2000-08-06' , '女');
('1007' , ‘王五’ , '2001-12-01' , '男');
('1008' , '李四' , NULL, '女');
('1009' , '李四' , NULL, '男');
('1010' , '李四' , '2001-12-01', '女');
select count(t1.birth) as c1
from (
select * from student_table where sex = '男' ) t1
right join
(select * from student_table where sex = '女') t2
on t1.birth = t2.birth and t1.name = t2.name ;
的结果行数是（）？
from (
select * from student_table where sex = '男' ) t1
right join
(select * from student_table where sex = '女') t2
on t1.birth = t2.birth and t1.name = t2.name ;
的结果行数是（）？
