Percent decrease in value each month with SQL I'm trying to make a field in MS SQL that will serve as a target field, and I would like for it to decrease automatically each month. For instance, starting in April with a target 99.4%, May would decrease to 98.8 and June would be 98.3? Is there an easy way yo do this with SQL that I'm not aware of? I've gone through and manually entered them in with a CASE STATEMENT but I would like for them to not be hard coded.
You can use a function/formula:

CREATE FUNCTION Sequence(@Date date)
RETURNS decimal(5,2) 
AS
BEGIN

DECLARE 
    @InitYear int = 2019,
    @InitValue decimal (5,2) = 93.60,
    @Decrement decimal (5,2) = 0.20,
    @MinValue decimal (5,2) = 90.60,
    @Result decimal(5,2) = 0;

    SET @Result = (@IniTValue 
                  - ((DATEPART(year, @Date) - @InitYear) * 12 * @Decrement))
                  - ((DATEPART(month, @Date)-1) * @Decrement);

    IF (@Result &lt; @MinValue)
        SET @Result = @MinValue;

    RETURN @Result;
END




SELECT dbo.Sequence ('20190101') AS '01/01/2019',
       dbo.Sequence ('20190201') AS '01/02/2019',
       dbo.Sequence ('20190301') AS '01/03/2019',
       dbo.Sequence ('20190401') AS '01/04/2019',
       dbo.Sequence ('20190501') AS '01/05/2019',
       dbo.Sequence ('20190601') AS '01/06/2019';

SELECT dbo.Sequence ('20200101') AS '01/01/2020',
       dbo.Sequence ('20200201') AS '01/02/2020',
       dbo.Sequence ('20200301') AS '01/03/2020',
       dbo.Sequence ('20200401') AS '01/04/2020',
       dbo.Sequence ('20200501') AS '01/05/2020',
       dbo.Sequence ('20200601') AS '01/06/2020';




01/01/2019 | 01/02/2019 | 01/03/2019 | 01/04/2019 | 01/05/2019 | 01/06/2019
:--------- | :--------- | :--------- | :--------- | :--------- | :---------
93.60      | 93.40      | 93.20      | 93.00      | 92.80      | 92.60     

01/01/2020 | 01/02/2020 | 01/03/2020 | 01/04/2020 | 01/05/2020 | 01/06/2020
:--------- | :--------- | :--------- | :--------- | :--------- | :---------
91.20      | 91.00      | 90.80      | 90.60      | 90.60      | 90.60     



db&lt;>fiddle here