Question

I have a long sql query that calculates a few things about payments and shipments. In some cases the value is null. I think that’s because there’s being divided by 0.

Here’s a small part of my query:

     ROUND(sum(case when shipping_method = 'c' AND (paid_amount - shipping_costs) < 70 then 1 end) * 100 / sum(case when shipping_method = 'c' then 1 end),2) as co_less_70,

I think that when this part is 0: sum(case when shipping_method = 'colissimo' then 1 end),2) my query shows null. Is there any way to assign a default value for this co_less_70 column?

Answer 1

Yes. You can use the COALESCE() function:

http://dev.mysql.com/doc/refman/5.0/en/comparison-operators.html#function_coalesce
Returns the first non-NULL value in the list, or NULL if there are no non-NULL values.

In your code:

COALESCE(
    ROUND(sum(case when shipping_method = 'c' AND (paid_amount - shipping_costs) < 70 then 1 end) * 100 / sum(case when shipping_method = 'c' then 1 end),2),
    0
) AS co_less_70