MySQL 8.0: Unexpected results when using CASE statement with COALESCE in SELECT query
After trying multiple solutions online, I still can't figure this out....... I am working with an scenario with a MySQL 8.0 query that uses a CASE statement combined with COALESCE. The intent is to select a value based on a condition, but I'm getting unexpected results when NULL values are involved. Here is the query I'm using: ```sql SELECT user_id, COALESCE( CASE WHEN status = 'active' THEN last_login ELSE NULL END, 'Never' ) AS last_login_display FROM users; ``` In this query, I expect `last_login_display` to show the `last_login` date for active users and 'Never' for all others. However, it seems that for users with `NULL` as `last_login`, the output is showing 'Never' for active users but not reflecting the actual `last_login` date for any `active` users who do have a valid date. I've tried to debug it by simplifying the CASE statement, and I even checked the data types of `last_login` and `status`. The `last_login` column is of type `DATETIME`, and I ensured that there are no formatting issues. Here’s a sample of the data from the `users` table: | user_id | status | last_login | |---------|---------|---------------------| | 1 | active | 2023-09-01 10:00:00 | | 2 | active | NULL | | 3 | inactive| 2023-08-15 08:45:00 | | 4 | active | NULL | Based on the above data, I expected the results to show the last login for user 1 and 'Never' for user 2 and 4. Instead, I'm getting 'Never' for user 1 as well. Is there an scenario with how COALESCE and CASE are being evaluated here? Any insights or solutions would be greatly appreciated! My development environment is macOS. Am I missing something obvious? My development environment is Windows. What am I doing wrong? I'm working on a service that needs to handle this. How would you solve this?