👀 Views: 54 💬 Answers: 1 📅 Created: 2025-06-03

postgresql sql null SQL

I tried several approaches but none seem to work. I'm encountering a frustrating issue with a SQL query that yields inconsistent results when run in my local development environment compared to the production environment. The query is meant to calculate the total sales for each product category grouped by month. In my local setup (PostgreSQL 14.1), it returns accurate results, but in production (PostgreSQL 13.3), I'm getting unexpected NULL values for some categories. Here's the SQL query I'm using: ```sql SELECT p.category, DATE_TRUNC('month', s.sale_date) AS sale_month, SUM(s.amount) AS total_sales FROM products p LEFT JOIN sales s ON p.id = s.product_id GROUP BY p.category, sale_month ORDER BY sale_month; ``` I've checked the data in both environments, and both seem to have the same structure and row counts. However, I've noticed that in production, some categories have no associated sales records in the `sales` table, which is expected, but rather than returning a total of 0 for these categories, they're showing up as NULL in the result set. To troubleshoot, I tried modifying the query to explicitly handle NULLs by adding a COALESCE function: ```sql SELECT p.category, DATE_TRUNC('month', s.sale_date) AS sale_month, COALESCE(SUM(s.amount), 0) AS total_sales FROM products p LEFT JOIN sales s ON p.id = s.product_id GROUP BY p.category, sale_month ORDER BY sale_month; ``` This change produced the desired output locally, but still returns NULL values for the same categories in production. I also checked the database settings for both environments and found no significant differences. Could this be related to any differences in default settings or how PostgreSQL handles NULLs in different versions? Any insights or suggestions on how to ensure consistent behavior across both environments would be greatly appreciated! My development environment is Ubuntu. Hoping someone can shed some light on this.