MySQL 8.0 - scenarios 1242: Subquery Returns More Than 1 Row in Conditional Expression
I'm currently working on a MySQL 8.0 database and trying to execute a query that involves a conditional expression using a subquery. However, I'm running into an `behavior 1242: Subquery returns more than 1 row` behavior message. Here’s the query I’m using: ```sql SELECT employee_id, (SELECT department_name FROM departments WHERE department_id = employees.department_id) AS department_name, (SELECT COUNT(*) FROM projects WHERE leader_id = employees.employee_id AND status = 'active') AS active_projects FROM employees WHERE employee_id IN (1, 2, 3); ``` The goal is to fetch the employee IDs along with their respective department names and the count of active projects they are leading. However, the subquery for the `department_name` seems to be causing issues because there are cases where multiple departments could match a single employee's `department_id` in the `departments` table. To troubleshoot, I've tried changing the subquery to limit the results using `LIMIT 1`, but it doesn't seem to be the best approach because I need to accurately reflect the department name. I've also attempted to handle potential duplicates in the `departments` table by ensuring that department IDs are unique, but it hasn't resolved the behavior. Is there a way to restructure this query to avoid the `behavior 1242` while ensuring that each employee is matched with their correct department? Any suggestions on best practices for handling such cases would be greatly appreciated! My development environment is macOS. Is there a better approach?