sql 函数定义报错，说时少了“；” ？

create function countByDept(deptName varchar(20)) returns integer
begin
declare cnt integer;
select count(*) into cnt
from Stu
where Stu.Sdept=deptName;
end

MySQL 数据库方式：

use test;
create function CountByDept(deptName varchar(20))
returns INT
begin
  declare cnt int;

  select sum(1) into cnt from Stu t
  where t.Sdept=deptName;

  return cnt;
end