Mysql: How to return just the main rows from two tables if condition from joined table doesnt match?

Question

maybe someone can help me. We have two tables:

• company_projects
• company_events

A company_project may have more than one event with different types (event_type_id). If a Project has a special event I want to remove it from the results even if it has other events.

This doesnt work:

SELECT cp.id, ce.event_type_id
FROM companies_projects cp
LEFT  JOIN companies_events ce ON ce.project_id = cp.id
WHERE ce.event_type_id != 219
GROUP BY cp.id

Table structure like this:

**company_projects**  
id  
project_type_id  
company_id  
...

**company_events**  
id  
project_id  
event_type_id
...

I just want to leave out the projects that have a special event, even if it has other events.

Answer 1

You need to exclude the project record, not the event, so:

SELECT cp.id, ce.event_type_id
FROM companies_projects cp
LEFT  JOIN companies_events ce ON ce.project_id = cp.id
WHERE cp.id NOT IN (
  SELECT cp.id FROM companies_projects cp
  LEFT  JOIN companies_events ce ON ce.project_id = cp.id
  WHERE ce.event_type_id = 219
)
GROUP BY cp.id

Answer 2

SELECT cp.id, ce.event_type_id
    FROM companies_projects cp
        LEFT JOIN companies_events ce 
            ON ce.project_id = cp.id
    WHERE NOT EXISTS(SELECT NULL 
                         FROM companies_events 
                         WHERE project_id = cp.id 
                             AND event_type_id = 219)