# Categories and their Subcategories using OR

**URL:** <https://meta.discourse.org/t/categories-and-their-subcategories-using-or/276583>\
**Category:** Data & reporting\
**Tags:** sql-query, sql-tutorial\
**Created:** [August 25, 2023, 8:37am UTC](https://meta.discourse.org/t/categories-and-their-subcategories-using-or/276583 "2023-08-25T08:37:03Z")\
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**Author:** ![JammyDodger](https://sea3.discourse-cdn.com/meta/user_avatar/meta.discourse.org/jammydodger/32/254611_2.png) [@JammyDodger](https://meta.discourse.org/u/JammyDodger)\
**Post date:** [August 25, 2023, 8:37am UTC](https://meta.discourse.org/t/categories-and-their-subcategories-using-or/276583/1 "2023-08-25T08:37:03Z")

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Sometimes you want to find information about topics that are in certain categories, plus all the topics in those categories’ subcategories too. You can add the category\_id of each subcategory to your query, but this can produce a pretty long list depending on your category/subcategory setup. 🙂

An alternative method is to add in the `categories` table and use `OR`:  
(Make sure to amend the value to be the one of your parent category)

```sql
SELECT 
    t.category_id,
    t.id AS topic_id
FROM topics t
  JOIN categories c ON c.id = t.category_id
WHERE (c.id = 5 OR c.parent_category_id = 5)

```

You can also use this with a parameter:

```sql
-- [params]
-- int :category_id

SELECT 
    t.category_id,
    t.id AS topic_id
FROM topics t
  JOIN categories c ON c.id = t.category_id
WHERE (c.id = :category_id OR c.parent_category_id = :category_id)

```

And to amend it for multiple categories with subcategories you can swop the parameter for an `int_list` version and adapt your query to use `IN` like so:

```sql
-- [params]
-- int_list :category_id

SELECT 
    t.category_id,
    t.id AS topic_id
FROM topics t
  JOIN categories c ON c.id = t.category_id
WHERE (c.id IN (:category_id) OR c.parent_category_id IN (:category_id))

```

Or hard-code the parent categories into the query itself:

```sql
SELECT 
    t.category_id,
    t.id AS topic_id
FROM topics t
  JOIN categories c ON c.id = t.category_id
WHERE (c.id IN (4, 5) OR c.parent_category_id IN (4, 5))

```

These queries are mainly examples to demonstrate the principles. Hopefully you find them useful, but if you have any questions please ask them below. 🙂

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