Sql Order By … using `Case When` for different Ascending, Descending, and Custom Orders

Question

I want to sort product by discount on certain condition

ORDER BY 
    CASE WHEN @OrderBy = 0
    THEN table.id END ASC,
    CASE WHEN @Orderby = 2
    THEN tabl         


        

Answer 1

Don't calculate the discount in the ORDER BY clause but in the SELECT

SELECT *, (100-(table.price/table.oldprice))*100 as discount
FROM table

...

ORDER BY 
CASE WHEN @OrderBy = 0
THEN table.id END ASC,
CASE when @orderby=2
THEN table.id END ASC,
CASE WHEN @OrderBy = 4
THEN discount END ASC