👀 Views: 32 💬 Answers: 1 📅 Created: 2025-07-22

MySQL GROUP_CONCAT SQL database

I've spent hours debugging this and I'm sure I'm missing something obvious here, but I'm working with MySQL 5.7 and trying to use the `GROUP_CONCAT` function to aggregate values from multiple rows into a single string based on a certain condition... However, I'm encountering issues where the results returned seem incomplete or do not include all expected values. Here's the query I wrote: ```sql SELECT category, GROUP_CONCAT(item ORDER BY item SEPARATOR ', ') AS items FROM products WHERE available = 1 GROUP BY category; ``` The `products` table has the following structure: ``` +----+----------+---------+----------+ | id | category | item | available| +----+----------+---------+----------+ | 1 | Fruit | Apple | 1 | | 2 | Fruit | Banana | 1 | | 3 | Fruit | Orange | 0 | | 4 | Vegetable| Carrot | 1 | | 5 | Vegetable| Lettuce | 1 | | 6 | Vegetable| Broccoli| 0 | +----+----------+---------+----------+ ``` When I run this query, I expect to get the following results: ``` +----------+-----------------------+ | category | items | +----------+-----------------------+ | Fruit | Apple, Banana | | Vegetable| Carrot, Lettuce | +----------+-----------------------+ ``` However, I am only getting: ``` +----------+-----------------------+ | category | items | +----------+-----------------------+ | Fruit | Apple, Banana | | Vegetable| Carrot | +----------+-----------------------+ ``` It seems like the items list for the `Vegetable` category isn't aggregating the lettuce properly. I've double-checked that all items in that category are marked as available. Also, I've tried running the query without the `available` condition, and it returns the correct results, which suggests that the filtering is somehow affecting my aggregation. I even experimented by changing the `GROUP BY` to include `available` as well, but that didn't help. Any ideas on what could be causing this issue or how I can ensure all available items are included in the `GROUP_CONCAT` output? Thanks in advance! I'd really appreciate any guidance on this. My development environment is Ubuntu 22.04. Any pointers in the right direction?