Question

I have previously asked the following question: Calculating percentage within the SQL

Now i was lucky enough to get a great answer however in my question i did not take into account that my rows could contain zero.

The questions row where simple:

select 
Number_of_Calls,
Number_of_Answered,
((Number_of_answered/Number_Of_Calls)*100) as answer_percent,
Date
from table Where Date BETWEEN '2012-09-10' AND '2012-09-11'

However Number_of_answered could be zero (if our company did not answer the calls) so if i want the full number in percentage how do i take 0 into account?

By the way. The database that we use is an Oracle database with PL SQL

Answer 1

The nullif function can be used to return null if the divisor is zero. When SQL encounters a null divisor it forces the entire equation to return null, preventing your error from occurring.

select 
Number_of_Calls,
Number_of_Answered,
((Number_of_answered/nullif(Number_Of_Calls,0))*100) as answer_percent,
Date
from table Where Date BETWEEN '2012-09-10' AND '2012-09-11'

If you would like to exclude null percentages use the following SQL:

select * from(select 
    Number_of_Calls,
    Number_of_Answered,
    ((Number_of_answered/nullif(Number_Of_Calls,0))*100) as answer_percent,
    Date
    from table Where Date BETWEEN '2012-09-10' AND '2012-09-11') alias
where answer_percent is not null;