Selecting data from 2 specific dates gives "Division by zero" error - postgresql

Question

I want to return data from yesterday and 8 days ago.
To do this I use the following line in my query:
WHERE (o.status_date::date = now()::date - INTERVAL '8 days')
OR (o.status_date::date = now()::date - INTERVAL '1 day')
However, this returns a "Division by zero" error. When I use only one of the two, so for example:
WHERE (o.status_date::date = now()::date - INTERVAL '8 days')
I get no error...
I don't understand where the error comes from, or perhaps I'm making a very straightforward mistake. Any help is appreciated!
Edited, these are the calculations done in my query:
SUM(CASE WHEN o.status_id = '12' THEN 1 ELSE 0 END) AS failed_63,
SUM(CASE WHEN o.status_id IN ('6','11','12','14','22','24') THEN 1 ELSE 0 END) AS total_orders,
ROUND(
(SUM(CASE WHEN o.status_id = '12' THEN 1 ELSE 0 END) * 100)::numeric /
(SUM(CASE WHEN o.status_id IN ('11','12','14','22','24') THEN 1 ELSE 0 END)), 2) AS perc_fail,
COUNT(DISTINCT i.order_id) AS order_issues,
ROUND(
(COUNT(DISTINCT i.order_id) * 100)::numeric / (SUM(CASE WHEN o.status_id IN ('11','12','14','22','24') THEN 1 ELSE 0 END)), 2) AS issue_rate,
SUM(CASE WHEN o.status_id = '6' THEN 1 ELSE 0 END) AS overdue_53,
ROUND(
(SUM(CASE WHEN o.status_id = '6' THEN 1 ELSE 0 END) * 100)::numeric /
(SUM(CASE WHEN o.status_id IN ('6','11','12','14','22','24') THEN 1 ELSE 0 END)), 2) AS perc_overdue,
ROUND(
(AVG(dop.vendor_confirmation_time)::numeric / 60), 2) AS avg_v_confirmation_time,
CASE
WHEN (AVG(dop.vendor_confirmation_time)::numeric / 60) < 3 THEN 'good'
WHEN (AVG(dop.vendor_confirmation_time)::numeric / 60) IS NULL THEN 'n/a'
ELSE 'bad'
END AS vendor_response

Answer 1

You have several cases in your query where your divisor might be 0, as in:
SUM(CASE WHEN o.status_id IN ('6','11','12','14','22','24') THEN 1 ELSE 0 END)
The best way to solve this is to use a sub-query to calculate all the sums, which are repeated anyway, and then do the division and rounding in the main query, where the divisor is not 0:
SELECT
sum12 AS failed_63,
sum6 + sum12 + sum11_24 AS total_orders,
CASE WHEN sum12 + summ11_24 > 0 THEN round(sum12 * 100. / (sum11_24 + sum 12), 2)
ELSE NULL END AS perc_fail,
order_issues,
CASE WHEN sum12 + summ11_24 > 0 THEN round(order_issues * 100. / (sum12 + sum11_24), 2)
ELSE NULL END AS issue_rate,
sum6 AS overdue_53,
CASE WHEN sum6 + sum12 + sum11_24 > 0 THEN round(sum6 / (sum6 + sum12 + sum11_24), 2)
ELSE NULL END AS perc_overdue,
round(avg_v_confirmation_time, 2) AS avg_v_confirmation_time,
CASE
WHEN (avg_v_confirmation_time) < 3 THEN 'good'
WHEN (avg_v_confirmation_time) IS NULL THEN 'n/a'
ELSE 'bad'
END AS vendor_response
FROM (
SELECT
sum(CASE WHEN o.status_id = '6' THEN 1 ELSE 0 END) AS sum6,
sum(CASE WHEN o.status_id = '12' THEN 1 ELSE 0 END) AS sum12,
sum(CASE WHEN o.status_id IN ('11','14','22','24') THEN 1 ELSE 0 END) AS sum11_24,
count(DISTINCT i.order_id) AS order_issues,
avg(dop.vendor_confirmation_time::numeric / 60) AS avg_v_confirmation_time
FROM o, i, dop
WHERE ... ) sub
In this case I set all columns where the divisor would be 0 to NULL; change as appropriate.
For future questions:
List your PostgreSQL version
Post the entire query with table qualifiers for all columns
Preferably, post the table structure

Answer 2

I still don't know why my first line didn't work, but I've now found a work-around by using the following:
WHERE o.status_date::date BETWEEN CURRENT_DATE - INTERVAL '8 days' AND CURRENT_DATE - INTERVAL '1 day'
AND o.status_date::date NOT BETWEEN CURRENT_DATE - INTERVAL '7 days' AND CURRENT_DATE - INTERVAL '2 days'