Oracle sqlover用法

--求和两种结果相同

select e.employee_id ,e.first_name,e.salary,sum(e.salary)

from employees e

group by e.employee_id ,e.first_name,e.salary;

select e.employee_id ,e.first_name,e.salary,sum(e.salary) over() sum

from employees e;

--求和

--第二行的sum=第一行里的sal+第二行里的sal;

-- 第二行的sum=第一行里的sal+第二行里的sal+第三行里的sal;

select e.employee_id,

e.department_id,

e.first_name,

e.salary,

sum(e.salary) over(order by e.first_name) sum

from employees e;

--每个sum的值都是把last_name相同的sal值进行求和。

select e.employee_id,

e.department_id,

e.last_name,

e.salary,

sum(e.salary) over(partition by e.last_name) sum

from employees e;