MySQL 5.7 - Unexpected Behavior with GROUP BY and Non-Aggregated Columns
This might be a silly question, but I tried several approaches but none seem to work. I'm experiencing unexpected behavior in MySQL 5.7 when using `GROUP BY` along with non-aggregated columns, and I'm unsure why it's happening. I have a query that looks like this: ```sql SELECT department, COUNT(employee_id) AS total_employees FROM employees GROUP BY department, salary; ``` I expected this to give me the total number of employees per department, but it seems to return the count of employees for each unique salary in that department. The result set is much larger than I anticipated. The output looks something like this: | department | total_employees | |------------|-----------------| | Sales | 5 | | Sales | 2 | | HR | 3 | | HR | 1 | I also read somewhere that MySQL allows this behavior because it only requires non-aggregated columns in the `SELECT` clause to be present in the `GROUP BY` for it to work, but I find this confusing. I tried modifying my query to: ```sql SELECT department, COUNT(employee_id) AS total_employees FROM employees GROUP BY department; ``` This gives me the correct total counts per department, but when I want to include other aggregated metrics (like average salary) alongside the total count, I ran into issues. For example: ```sql SELECT department, AVG(salary) AS avg_salary, COUNT(employee_id) AS total_employees FROM employees GROUP BY department; ``` This gives the correct result, but I still want to understand why the initial query was behaving the way it did. Is it a quirk of MySQL, or is there some setting I need to adjust to get consistent results with `GROUP BY` and non-aggregated fields? Any insights into this would be greatly appreciated. For context: I'm using Sql on Ubuntu. My development environment is Windows. Am I missing something obvious?