Who gets filtered by WHERE d.id IS NULL?

Question

Accepted Answer

LEFT JOIN + WHERE right_table.id IS NULL is the classic pattern for finding rows in the left table with no match in the right table. Alice matches Sales, so d.id = 10 and she is excluded by WHERE. Bob (NULL dept_id) and Carol (dept_id 99, no matching dept) both produce d.id = NULL and pass the filter.