在MySQL提起從其他計算領域

Question

我尋求一種方法，能寫這樣的事情

select complicated_calculation1 as comp1, 
complicated_calculation2 as comp2, 
(comp1/comp2) as percent 
from table 

，而不是像這樣

select complicated_calculation1 as comp1, 
complicated_calculation2 as comp2, 
(complicated_calculation1/complicated_calculation2) as percent 
from table 

在更爲複雜的方式寫它計算的是這可能嗎？

Answer 1

不在同一行。

你可以做的是：

SELECT comp1, comp2, (comp1/comp2) as percent FROM(
select complicated_calculation1 as comp1, 
complicated_calculation2 as comp2 
from table) AS t 

Answer 2

no u cann't use this 

select complicated_calculation1 as comp1, 
complicated_calculation2 as comp2, 
(comp1/comp2) as percent 
from table 

u have to use only this 

select complicated_calculation1 as comp1, 
complicated_calculation2 as comp2, 
(complicated_calculation1/complicated_calculation2) as percent 
from table 

because rantime calculation can not be applied on Alis field name