Postgresql query with double has_many relationships - postgresql

Question

I have this complex data relationship.
POSTGRESQL FIDDLE: https://www.db-fiddle.com/f/vm2z8qLuddzcHEgyaMnCbc/3
"Item Group" has many "items" through "item_ads" table.
So an Item Group has many part_number.
reports table contains the number of clicks for each day for each adgroupid.
Each adgroupid has_many part_numbers. (table: product_ads)
Now, I want to SUM all reports.clicks for each item_groups.id using the part_number to linked the tables.
After this, I have to consider only reports.adgroupid which are included in the part_numbers of item_group. So if "Item group" has three part_number (A, B, C) can be considered all adgroupid that contains A,B, or C but nothing more. If adgroupid contains part_number D it cannot be considered for clicks sum.
Expected results
I have to have a table with lots of item_group_ids.
I am looking for the PostgreSQL query to achieve this table.

Answer 1

First, let's build the query up in parts. It sounds like you already know how to get from item_group and adgroup to part_number, just not about how to join them. I've added a query that removes duplicates for part 1 of your question, but putting them into a CTE:
WITH unique_part_numbers AS (
SELECT DISTINCT item_groups.id AS item_group_id,
part_number
FROM item_groups
JOIN item_ads ON item_group_id = item_groups.id
JOIN items ON items.id = item_ads.item_id
)
SELECT unique_part_numbers.item_group_id, SUM(clicks)
FROM unique_part_numbers
JOIN product_ads ON product_ads.part_number = unique_part_numbers.part_number
JOIN reports ON product_ads.adgroupid = reports.adgroupid
GROUP BY item_group_id
About the second part - it's not possible to do it as you want, because you can have multiple adgroups per item_group - so I added adgroupid as an extra column. I create an array of part_numbers for the adgroup and check, using the #> operator, that all parts that are from the adgroupid are also from the unique_part_numbers.item_group_id.
WITH unique_part_numbers AS (
SELECT DISTINCT item_groups.id AS item_group_id,
part_number
FROM item_groups
JOIN item_ads ON item_group_id = item_groups.id
JOIN items ON items.id = item_ads.item_id
)
SELECT unique_part_numbers.item_group_id,
product_ads.adgroupid,
array_agg(unique_part_numbers.part_number),
SUM(clicks)
FROM unique_part_numbers
JOIN product_ads ON product_ads.part_number = unique_part_numbers.part_number
JOIN reports ON product_ads.adgroupid = reports.adgroupid
GROUP BY item_group_id, product_ads.adgroupid
HAVING array_agg(product_ads.part_number) #> (
SELECT ARRAY_AGG(other_product_ads.part_number)
FROM product_ads AS other_product_ads
WHERE other_product_ads.adgroupid = product_ads.adgroupid
)