if(A1<65,0,(IF(65<=A1 && A1<70,A1*0.7,IF(70<=A1 && A1<80,A1*0.8,IF(80<=A1 && A1<90,A1*0.9,IF(A1>=90,A1,0))))))

sql server 上的代码：

drop table if exists dbo.dongdutaizi;

create table dbo.dongdutaizi ( 区间 int not null,支付系数 float)

INSERT INTO [dbo].[DongDuTaiZi]  VALUES (N'0', N'0')

GO

INSERT INTO [dbo].[DongDuTaiZi]  VALUES (N'65', N'0.7')

GO

INSERT INTO [dbo].[DongDuTaiZi]  VALUES (N'70', N'0.8')

GO

INSERT INTO [dbo].[DongDuTaiZi]  VALUES (N'80', N'0.9')

GO

INSERT INTO [dbo].[DongDuTaiZi]  VALUES (N'90', N'1')

GO

declare @i int = 64

select max(支付系数) from dbo.dongdutaizi where @i >= 区间 ;