-- 积分短为 col
select (case when col <= 5000 then col
             when col > 5000 and col <= 30000 then 5000+(col-5000)*0.02
             when col > 30000 and col <= 50000 then 5000+25000*0.02+(col-30000)*0.03
             when ... end)
from tb

-- 类似写下去！

------解决方案--------------------

SQL code
create table TB(积分 int)
insert into TB select 67500
insert into TB select 125412
go
select 积分,
(case when 积分>5000 and 积分<=30000 then 积分*0.02
     when 积分>30000 and 积分<=50000 then 600+(积分-30000)*0.03
     when 积分>50000 and 积分<=100000 then 1200+(积分-50000)*0.04
     when 积分>100000 then 2000+(积分-100000)*0.05
end)返还金额
from tb
/*
积分          返还金额
----------- ---------------------------------------
67500       1900.00
125412      3270.60

(2 行受影响)

*/
go
drop table tb