MySQL stored procedure does not return expected results when using multiple OUT parameters
This might be a silly question, but I'm confused about I'm working on a project and hit a roadblock. I'm working with a MySQL stored procedure where I intend to retrieve multiple aggregated values based on user input. However, when I execute the procedure, I'm working with unexpected results, particularly with the OUT parameters not reflecting the correct values. Here’s a simplified version of my stored procedure: ```sql DELIMITER $$ CREATE PROCEDURE GetUserStatistics(IN userId INT, OUT totalOrders INT, OUT totalSpent DECIMAL(10, 2)) BEGIN SELECT COUNT(*) INTO totalOrders FROM orders WHERE user_id = userId; SELECT SUM(amount) INTO totalSpent FROM orders WHERE user_id = userId; END $$ DELIMITER ; ``` When I call this stored procedure like this: ```sql CALL GetUserStatistics(1, @orders, @spent); SELECT @orders, @spent; ``` I expect `@orders` to contain the total number of orders for the user and `@spent` to show the total amount spent. However, `@orders` shows `0` and `@spent` shows `NULL` even when I know there are records in the `orders` table for `user_id = 1`. I’ve checked that there are indeed orders for the user by running: ```sql SELECT COUNT(*) FROM orders WHERE user_id = 1; ``` This returns a positive count, so I'm unsure why the values are not being set correctly in the procedure. I've also tried using `SET totalOrders = 0;` and `SET totalSpent = 0;` before the SELECT statements, but it doesn’t seem to help. I am using MySQL version 8.0.26. Could there be an scenario with the way I'm handling OUT parameters, or is it possible that there's a logic behavior elsewhere in the procedure? Any insights would be greatly appreciated! Am I missing something obvious? The project is a service built with Sql. Is this even possible? I'm coming from a different tech stack and learning Sql.