Multiple Categories on Topics

data & reporting
1

Hello, i am trying to get the multiple categories on topics, example https://www.waze.com/discuss/t/trouble-installing/13068
when i try going into the topics table i only see 1 of the categories in this dataset, i would like to know how possible it’s to get both categories related to this topic.

Thank you in advance,

2

Hi Josia, welcome! :wave:

I can’t access your link, or log in. Maybe you could provide a screenshot instead?

3

A7UCov5SHng9rKf
A7UCov5SHng9rKf814×130 8.07 KB

Here as you can see there is a category and a sub-category i want to be able to see them both.

4

The category table contains a parent_category_id containing the ID of the parent category, or NULL if the category doesn’t have a parent. To get both categories, you probably want to LEFT JOIN to the category table a second time, something like this:

SELECT
    t.id as topic_id,
    c.id as category_id,
    pc.id as parent_category_id
FROM topics t
INNER JOIN categories c ON t.category_id = c.id
LEFT JOIN categories pc ON c.parent_category_id = pc.id
LIMIT 20
3 Likes
5

Thank you for the help.

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6

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