oracle统计函数统计各个年份入职的人数

--统计各个部门各个年份的入职人数  --还有一个人不属于任何部门
  select
    e.department_id,
    d.department_name,
   count(*) total,
    sum(decode(to_char(hire_date,'yyyy'),'2001',1,0))    "2001",
       sum(decode(to_char(hire_date,'yyyy'),'2002',1,0)) "2002",
       sum(decode(to_char(hire_date,'yyyy'),'2003',1,0)) "2003",
       sum(decode(to_char(hire_date,'yyyy'),'2004',1,0)) "2004",
       sum(decode(to_char(hire_date,'yyyy'),'2005',1,0)) "2005",
       sum(decode(to_char(hire_date,'yyyy'),'2006',1,0)) "2006",
       sum(decode(to_char(hire_date,'yyyy'),'2007',1,0)) "2007",
       sum(decode(to_char(hire_date,'yyyy'),'2008',1,0)) "2008"
    from emp e,departments d  where e.department_id=d.department_id(+)  group by   e. department_id,d.department_name            
                         -- where e.department_id=20