Informix divide by zero error

Question

I have a query which is erroring out with a divide by zero error. I have isolated the part of the query which errors and tried to fix it using an NVL but it's just not going well, can someone spot my error?

select  warehouse.ware_code,
    warehouse.desc_text,
    maingrp.maingrp_code,
    maingrp.desc_text,
    prodgrp.prodgrp_code,
    prodgrp.desc_text,
    left(product.part_code,7) Parent_Product_code,
    product.part_code,
    product.desc_text,
    sum(salesstat.order_qty - salesstat.return_qty) Total_Sales,
    sum((salesstat.order_qty - salesstat.return_qty) / 6) Average_Weekly_Sales,
    sum(((salesstat.order_qty - salesstat.return_qty) / 6) * 4) Average_Monthly_Sales,
    '??' Note,
    sum(prodstatus.onhand_qty) Stock_On_Hand,
    sum(orderstat.order_qty - orderstat.cancel_qty) Outstanding_orders,
    sum(prodstatus.onhand_qty - (orderstat.order_qty - orderstat.cancel_qty)) Stock_Available,
    --CASE
    --WHEN nvl(sum(salesstat.order_qty - salesstat.return_qty),0) = 0
    --  THEN 999
    --ELSE  sum(prodstatus.onhand_qty / ((salesstat.order_qty - salesstat.return_qty) / 6))
    --END as Weeks_Stock_Remaining,
    '??' Stock_ordered,
    '??' Production_date
from
    warehouse,
    warereptdetl,
    maingrp,
    prodgrp,
    product,
    prodstatus,
    salesstat,
    orderstat,
    Statint
where   warehouse.cmpy_code = maingrp.cmpy_code
and warehouse.cmpy_code = warereptdetl.cmpy_code
and warehouse.cmpy_code = prodgrp.cmpy_code
and warehouse.cmpy_code = product.cmpy_code
and warehouse.cmpy_code = salesstat.cmpy_code
and warehouse.cmpy_code = prodstatus.cmpy_code
and warehouse.cmpy_code = orderstat.cmpy_code
and warehouse.cmpy_code = statint.cmpy_code
and product.ware_code = prodstatus.ware_code
and product.ware_code = warehouse.ware_code
and product.ware_code = salesstat.ware_code
and product.ware_code = orderstat.ware_code
and product.ware_code = warereptdetl.ware_code
and product.part_code = salesstat.part_code
and product.part_code = orderstat.part_code
and product.part_code = prodstatus.part_code
and product.prodgrp_code = salesstat.prodgrp_code
and product.prodgrp_code = orderstat.prodgrp_code
and product.prodgrp_code = prodgrp.prodgrp_code
and product.maingrp_code = salesstat.maingrp_code
and product.maingrp_code = orderstat.maingrp_code
and product.maingrp_code = maingrp.maingrp_code
and salesstat.year_num = statint.year_num
and salesstat.int_num = statint.int_num
and salesstat.stat_type_code = statint.type_code
and orderstat.year_num = statint.year_num
and orderstat.int_num = statint.int_num
and orderstat.stat_type_code = statint.type_code
and warehouse.cmpy_code = 'AB'
and warereptdetl.warereptgrp_code = 'NSW'
and product.ware_code = 'HP1'
and product.status_ind <> 3
and left(product.part_code,2) = '21'
and statint.year_num = 2016
and statint.int_num between 29 AND 34
--and   statint.int_num = 29
and statint.type_code = 'WLY'
Group by 1,2,3,4,5,6,7,8,9

The commented out part is where I have tried to put in a fix, if I comment it out the query runs fine (albeit a bit slow).

The second part of the question is something that you may not be able to answer without having access to my database but if I run the query for 1, 2 or even 3 weeks (statint.int_num) the query comes back in under 1 minute. as soon as I push it out to 6 weeks (which is what I need) the query takes just over 40 minutes to return the results.

I can't see anywhere in the query where I have created a cartesian but I have stared at it for so long I may be missing it.

Answer 1

In your case statement:

sum(salesstat.order_qty - salesstat.return_qty)

may be non zero, but the individual

salesstat.order_qty - salesstat.return_qty

which is what you're dividing by, may contain zeroes.

EDIT

To clarify,

sum(prodstatus.onhand_qty / ((salesstat.order_qty - salesstat.return_qty) / 6))

may have zeroes in the denomiator because it is a sum of several fractions. Just because all of the denominators sum up to a non-zero number doesn't mean that all the denominators are non-zero.