Hvordan man betinget håndterer division med nul med MySQL

Ja, du kan lave en sag:

select case when noOfGirls=0 then noOfBoys 
       else  round(noOfBoys/noOfGirls) end as ration 
from student;

Men du vil sikkert gerne:

select case when noOfGirls=0 then 1 
       else  round(noOfBoys/noOfGirls) end as ration 
from student;