We need to have this query: All contacts not applied to selected event
SELECT c.* FROM CONTACTS c
LEFT JOIN EVENT_CONTACTS ec
ON c.ID = ec.ID_contact AND ec.ID_event = [linked to table Events Object manager instances.ID]
WHERE ec.ID_contact IS NULL;
But don't know how to add WHERE ec.ID_contact IS NULL condition to JOIN in LCA query structure
This is already configured:

Hi Harald,
Maybe I am overlooking something, but I believe that the filter section will implement your "where" condition in your SQL query.
Hi Harald,
As Miguel pointed out, you might want to use the Filter operation you have at the end of the query.
If you want to remove those results with an empty EVENT_CONTACTS.ID_contact you can use the Not Regex condition and set as filter value a dot "."
For example:

Do you have an example of what the dataset looks like without the filter on ID_Event?