MySQL 8.0: Inconsistent Results When Using GROUP BY with NULL and Empty Strings
I've been struggling with this for a few days now and could really use some help... I'm working on a project and hit a roadblock... I'm encountering an issue with MySQL 8.0 where my queries produce inconsistent results when grouping by a column that can contain both NULL values and empty strings. My table structure is as follows: ```sql CREATE TABLE users ( id INT AUTO_INCREMENT PRIMARY KEY, name VARCHAR(255) NOT NULL, email VARCHAR(255), status VARCHAR(10) ); ``` In this scenario, I have rows where `status` can either be NULL or an empty string. For example, I have the following records: ```sql INSERT INTO users (name, email, status) VALUES ('Alice', 'alice@example.com', NULL), ('Bob', 'bob@example.com', ''), ('Charlie', 'charlie@example.com', NULL), ('David', 'david@example.com', 'active'); ``` When I run the following query to count users by their `status`: ```sql SELECT status, COUNT(*) AS count FROM users GROUP BY status; ``` I expect the output to be: ``` +--------+-------+ | status | count | +--------+-------+ | NULL | 2 | | | 1 | | active | 1 | +--------+-------+ ``` However, I am getting the following results instead: ``` +--------+-------+ | status | count | +--------+-------+ | | 2 | | active | 1 | +--------+-------+ ``` It seems that both the NULL and empty string values are being counted together as empty. I have tried using different options for handling NULLs, such as: ```sql SELECT IFNULL(status, 'NULL') AS status, COUNT(*) AS count FROM users GROUP BY status; ``` But this does not resolve the underlying issue. I also attempted to use a case statement: ```sql SELECT CASE WHEN status IS NULL THEN 'NULL' ELSE status END AS status, COUNT(*) AS count FROM users GROUP BY status; ``` Yet, the results remain the same. I want to differentiate between NULL and empty string in my results. Is there a known behavior in MySQL regarding this, or is there something I might be missing in my query? Any help would be greatly appreciated! I recently upgraded to Sql 3.10. Any advice would be much appreciated. Any feedback is welcome!