MySQL 8.0 - implementing Decimal Precision in Aggregated Calculations
I'm sure I'm missing something obvious here, but I'm working with a strange question with MySQL 8.0 when performing aggregated calculations on DECIMAL fields. Specifically, I've got a table that tracks transactions, and I need to calculate the total amount spent by each user. However, the results seem to have an unexpected precision loss. My table structure looks like this: ```sql CREATE TABLE transactions ( id INT AUTO_INCREMENT PRIMARY KEY, user_id INT NOT NULL, amount DECIMAL(10, 2) NOT NULL, created_at DATETIME DEFAULT CURRENT_TIMESTAMP ); ``` I've been using the following query to get the total amount for each user: ```sql SELECT user_id, SUM(amount) AS total_spent FROM transactions GROUP BY user_id; ``` The amounts in the `amount` column are stored correctly with two decimal places, but when I run the aggregation, the `total_spent` sometimes shows values like `100.500000`, which should be `100.50`. I've tried casting the result as DECIMAL(10, 2) like this: ```sql SELECT user_id, CAST(SUM(amount) AS DECIMAL(10, 2)) AS total_spent FROM transactions GROUP BY user_id; ``` But this hasn't resolved the scenario. I've also checked my MySQL configuration settings, particularly `sql_mode`, and it includes `NO_ZERO_DATE` and `STRICT_TRANS_TABLES`, but I need to see how this would affect decimal precision. Any insight into why I'm experiencing this or how I can ensure my aggregated sums maintain the correct format? Has anyone else encountered similar issues with MySQL 8.0? I'm working on a CLI tool that needs to handle this. Any ideas what could be causing this? This is part of a larger CLI tool I'm building.