SQL / T-SQL按等级更新列

问题描述

create table Employees (
    EMP_ID INT,SALARY INT
);
insert into Employees (EMP_ID,SALARY) values (1,1954);
insert into Employees (EMP_ID,SALARY) values (2,1360);
insert into Employees (EMP_ID,SALARY) values (3,3366);
insert into Employees (EMP_ID,SALARY) values (4,7765);
insert into Employees (EMP_ID,SALARY) values (5,4445);
insert into Employees (EMP_ID,SALARY) values (6,7064);
insert into Employees (EMP_ID,SALARY) values (7,5757);
insert into Employees (EMP_ID,SALARY) values (8,6562);
insert into Employees (EMP_ID,SALARY) values (9,5279);
insert into Employees (EMP_ID,SALARY) values (10,7283);
 

第二张表

create table Sales (
    EMP_ID INT,Amount INT
);
insert into Sales (EMP_ID,Amount) values (6,14254);
insert into Sales (EMP_ID,Amount) values (4,16208);
insert into Sales (EMP_ID,12818);
insert into Sales (EMP_ID,15381);
insert into Sales (EMP_ID,17029);
insert into Sales (EMP_ID,Amount) values (10,19704);
insert into Sales (EMP_ID,Amount) values (9,10030);
insert into Sales (EMP_ID,Amount) values (2,10416);
insert into Sales (EMP_ID,Amount) values (3,13993);
insert into Sales (EMP_ID,Amount) values (1,18381);
insert into Sales (EMP_ID,Amount) values (5,12855);
insert into Sales (EMP_ID,Amount) values (8,10215);
insert into Sales (EMP_ID,15046);
insert into Sales (EMP_ID,17121);
insert into Sales (EMP_ID,10556);
insert into Sales (EMP_ID,16914);
insert into Sales (EMP_ID,16786);
insert into Sales (EMP_ID,12797);
insert into Sales (EMP_ID,14005);
insert into Sales (EMP_ID,18943);   

我需要按条件更新员工薪水：等级1（+ 15％）等级 2（+ 10％）在其他表中按平均销售额排名3（+ 5％）。 只需要更新前3名 因此，在第一步中，我使用Dense_Rank

SELECT e.EMP_ID,AVG (Amount) as 'AVG_Amount',DENSE_RANK () OVER (ORDER BY AVG (Amount) DESC) AS 'DR'
          FROM Employees e JOIN Sales s ON e.EMP_ID=s.EMP_ID
          GROUP BY e.EMP_ID



   EMP_ID    AVG_Amount DR       
         10        19704    1
        1          17751    2
        6          15195    3
        5          14884    4
        4          14802    5
        3          13945    6
        8          13668    7
        2          10416    8
        9          10030    9

我不了解下一步。我认为需要循环+ ifs + update ...

请帮助

解决方法

您可以使用case表达式。预聚合子查询，然后join：

select 
    e.emp_id,s.avg_amount,e.salary,d.rn,salary * case s.rn
        when 1 then 1.15
        when 2 then 1.1
        when 3 then 1.05
        else 1
    end as new_salary
from employees e 
inner join (
    select 
        emp_id,avg(amount) avg_amount,dense_rank () over (order by avg (amount) desc) as rn
    from sales
    group by emp_id
) s on s.emp_id = e.emp_id
order by d.rn

如果要使用update语句：

update e
set e.salary = 
    e.salary * case s.rn
        when 1 then 1.15
        when 2 then 1.1
        when 3 then 1.05
    end
from employees e 
inner join (
    select 
        emp_id,dense_rank () over (order by avg (amount) desc) as rn
    from sales
    group by emp_id
) s on s.emp_id = e.emp_id
where s.rn <= 3

Demo on DB Fiddle ：

emp_id | avg_amount | salary | rn | new_salary
-----: | ---------: | -----: | -: | ---------:
    10 |      19704 |   7283 |  1 |    8375.45
     1 |      17751 |   1954 |  2 |    2149.40
     6 |      15195 |   7064 |  3 |    7417.20
     5 |      14884 |   4445 |  4 |    4445.00
     4 |      14802 |   7765 |  5 |    7765.00
     3 |      13945 |   3366 |  6 |    3366.00
     8 |      13668 |   6562 |  7 |    6562.00
     2 |      10416 |   1360 |  8 |    1360.00
     9 |      10030 |   5279 |  9 |    5279.00