SQL Server: Unexpected NULL values in calculated column when using complex CASE statement
I've been struggling with this for a few days now and could really use some help. I'm building a feature where Could someone explain Hey everyone, I'm running into an issue that's driving me crazy. I've searched everywhere and can't find a clear answer. I am working with an scenario where a calculated column in my SQL Server 2017 database is returning unexpected NULL values. The calculated column is intended to categorize users based on their last login date, using a complex `CASE` statement. However, certain rows are coming back as NULL, which is not the expected behavior. Here’s the SQL for the calculated column: ```sql ALTER TABLE Users ADD UserCategory AS ( CASE WHEN LastLogin IS NULL THEN 'Inactive' WHEN DATEDIFF(DAY, LastLogin, GETDATE()) < 30 THEN 'Active' WHEN DATEDIFF(DAY, LastLogin, GETDATE()) BETWEEN 30 AND 90 THEN 'Dormant' ELSE 'Inactive' END ); ``` I have verified that `LastLogin` has valid date values for most rows. To troubleshoot, I ran a query to explicitly check the conditions: ```sql SELECT UserID, LastLogin, CASE WHEN LastLogin IS NULL THEN 'Inactive' WHEN DATEDIFF(DAY, LastLogin, GETDATE()) < 30 THEN 'Active' WHEN DATEDIFF(DAY, LastLogin, GETDATE()) BETWEEN 30 AND 90 THEN 'Dormant' ELSE 'Inactive' END AS UserCategory FROM Users; ``` In the result set, I noticed that for some users, even when `LastLogin` is not NULL, the `UserCategory` is still NULL. I suspect there might be an scenario with the `DATEDIFF` calculation, but I need to pinpoint the question. I've also tried simplifying the `CASE` statement to just return the active users and verified that works correctly. But reintroducing the full logic leads back to the NULL outputs. Any thoughts on why this might be happening or how to resolve this? For context: I'm using Sql on Ubuntu. Any help would be greatly appreciated! My development environment is Ubuntu. Thanks in advance! This is my first time working with Sql 3.9. Is there a better approach? Has anyone dealt with something similar? I've been using Sql for about a year now. Any pointers in the right direction? Could this be a known issue?