Question: Please list the categories of the app users who are not active when event no.2 happened.
SQL: SELECT DISTINCT T1.category FROM label_categories AS T1 INNER JOIN app_labels AS T2 ON T1.label_id = T2.label_id INNER JOIN app_events AS T3 ON T2.app_id = T3.app_id WHERE T3.event_id = 2 AND T3.is_active = 0