看似简单的一道SQL面试题，你是否能够很快写出答案？

create table student (
      id varchar(20),
      name varchar(20),
      gender char(1),
      birth varchar(20),
      department varchar(20),
      address varchar(20)
) charset = utf8;

insert into student values
("201901","张大佬","男","1985","计算机系","北京市海淀区"),
("201902","郭大侠","男","1986","中文系","北京市昌平区"),
("201903","张三","女","1990","中文系","湖南省永州市"),
("201904","李四","男","1990","英语系","辽宁市阜新市"),
("201905","王五","女","1991","英语系","福建省厦门市"),
("201906","王六","男","1988","计算机系","湖南省衡阳市");

select 
    department 院系,
    case gender when "男" then 1 else 0 end 男,
    case gender when "女" then 1 else 0 end 女
from student;

select 
      院系,
      sum(男) 男,
      sum(女) 女,
      sum(男) + sum(女) as 总计
from
(
    select department 院系,
    case gender when "男" then 1 else 0 end 男,
    case gender when "女" then 1 else 0 end 女
    from student
) a
group by 院系;