Simple Query – what’s wrong with it?

SELECT * 
FROM buildings
WHERE building_name NOT IN (SELECT building FROM employees)

I’m trying to answer exercise 2 with the above (try it yourself here: https://sqlbolt.com/lesson/select_queries_with_nulls), but it’s not returning anything. Is it a problem with the site or my query?

Thanks!

Answer

I checked your query, according to the question that was on the site, you can easily extract the desired data using a sub-query.

in this query first of all we get list of building name that have employees after that get list of building not have any employees

select * 
from buildings 
where building_name not in (select building  
                            from employees 
                            where building not null  
                            group by building)