日期之间的聚合

Question

我有以下问题，我试图计算一年中的工资总额。

select sum(case when date_key between to_char(sysdate,'yyyymm')
                                  and to_char(add_months(sysdate,-12), 'yyyymm')
                then salary end) as annual_salary 
from employee
group by emp_key

当我执行查询时，我在结果集中得到空值。

我实际上在员工表中有工资的有效数字。 我哪里错了？

Answer 1

只需反转2个边界，它们的顺序不正确：

...
between to_char(add_months(sysdate,-12), 'yyyymm')
   and to_char(sysdate,'yyyymm')

Answer 2

select 
sum(case when date_key between to_char(sysdate,'yyyymm') and to_char(add_months(sysdate,-12),'yyyymm') then salary else 0 end) as annual_salary 
from employee group by emp_key

当expr1 ELSE expr2结束时的情况 如果你没有＆＃34; ELSE expr2＆＃34; Oracle认为它是空的

Answer 3

select sum(case when date_key between 
                                   to_char(add_months(sysdate,-12), 'yyyymm') and to_char(sysdate,'yyyymm')
                then salary end) as annual_salary 
from employee
group by emp_key