PostgreSQL aggregate function with GROUP BY returning incorrect sums when using JOINs
I'm having trouble with I tried several approaches but none seem to work..... I'm running into an scenario where an aggregate function in my PostgreSQL query is not returning expected results when I join multiple tables. I'm trying to calculate the total sales per product category, but it seems that the sums are incorrect due to the way I'm joining the tables. Here's the query I'm using: ```sql SELECT pc.category_name, SUM(s.amount) AS total_sales FROM product_categories pc JOIN products p ON pc.id = p.category_id JOIN sales s ON p.id = s.product_id GROUP BY pc.category_name; ``` The `sales` table has multiple entries for each product for different transactions. I expected the `total_sales` for each `category_name` to reflect the correct aggregated amounts, but the results seem inflated and don't match the expected totals when I verify against the raw data. I've tried to isolate the question by running the `JOIN`s one at a time, and the `SUM(s.amount)` works correctly without the `JOIN`s. However, once I add the `JOIN`s back, the totals get skewed. I'm using PostgreSQL version 14.1 and noticed that when I select the distinct records from the `sales` table, the output has duplicates for some products when joined with the `products` table. Could this be due to how the joins are set up? Should I consider using a `DISTINCT` clause in my aggregation, or is there a better way to ensure accurate totals? Any insights would be appreciated! This is happening in both development and production on Windows 10.