Question

if i managed to make the folowing view in mysql

select id,name,score,total,CALCIT(total - score) as x,(CALCIT(total - score) / total) as per from tblx;

the process CALCIT(total – score) is being caculated two times

how to do some thing like this:

select id,name,score,total,CALCIT(total - score) as `x`,`x`/total as per from tblx; 

where CALCIT is a function

Answer 1

Try something like this:

select *, x/total from (
    select id,name,score,total,CALCIT(total - score) as x from tblx; 
) as tblx