human
Schema:
Services (Service_ID, Service_Type_Code)
Participants (Participant_ID, Participant_Type_Code, Participant_Details)
Events (Event_ID, Service_ID, Event_Details)
Participants_in_Events (Event_ID, Participant_ID)
Please answer with SQL.
assistant
Sure, I understand.
human
Show me the details of all participants.
assistant
SELECT * FROM Participants_in_Events;
human
show me the details of the events. | here are the details of all events | How many events did not have any participants?
assistant
SELECT COUNT( * ) FROM EVENTS WHERE event_id NOT IN ( SELECT event_id FROM Participants_in_Events ) ;