PostgreSQL: implementing Recursive CTE when fetching hierarchical data with varying depth
I'm stuck trying to I'm getting frustrated with After trying multiple solutions online, I still can't figure this out. I'm working on a personal project and I'm trying to fetch hierarchical data from a PostgreSQL database using a recursive Common Table Expression (CTE). The setup involves a `categories` table that has a parent-child relationship through a `parent_id` column. However, I'm working with an unexpected scenario when the depth of the hierarchy varies. Specifically, I only get results for categories that are direct children of the root category, while deeper levels return no data. Here's the SQL query I've been using: ```sql WITH RECURSIVE category_hierarchy AS ( SELECT id, name, parent_id FROM categories WHERE parent_id IS NULL UNION ALL SELECT c.id, c.name, c.parent_id FROM categories c INNER JOIN category_hierarchy ch ON ch.id = c.parent_id ) SELECT * FROM category_hierarchy; ``` I expect this query to return all categories, but it seems like only the first level of children is included. I've verified that there are indeed multiple levels of hierarchy in the `categories` table, and I'm using PostgreSQL 13.3. I also tried modifying the join condition in the recursive part but to no avail. I’ve attempted to debug by adding a `SELECT` statement inside the CTE to see what’s being fetched at each level, but it didn’t provide any insights. Is there something I'm missing in my recursive query, or is there a better approach to handle fetching hierarchical data in PostgreSQL? I'm working on a web app that needs to handle this. This is part of a larger API I'm building. Any help would be greatly appreciated! For reference, this is a production mobile app. Is this even possible? My development environment is Windows 11. Is this even possible?