问如何用高效的查询替换许多"IF's“

EN

select (case when afp = 1 and health = 1 then 0.05
             when afp = 1 and health = 2 then 0.10
             when afp = 1 and health = 3 then 0.15
             when afp = 2 and health = 1 then 0.07
             when afp = 2 and health = 2 then 0.12
             when afp = 2 and health = 3 then 0.18
        end) as discount

select t.*, v.discount
from t left join
     (values (1, 1, 0.05), (1, 2, 0.10), . . .
     ) v(afp, health, discount)
     on t.afp = v.afp and t.health = v.health

Select Discount = choose(aft,.05,.10,.15) + choose(health,.02,.02,.03)
 From  YourTable