MySQL选择与左连接不同？

Question

I am trying to get a list of company_id 's that have no company-level notes. The company may, however, have location-level notes.

company
-------------------------
company_id  name  deleted
1           Foo   0
2           Bar   0
3           Baz   0

location
-----------------------
location_id  company_id
6            1
7            2
8            3

note
-----------------------------------------
note_id  company_id  location_id  deleted
10       2           6            0         // location-level note
11       1           7            0         // location-level note
12       null        8            0         // location-level note
13       2           null         0         // company-level note

I would want my result table to be this:

company_id  name
1           Foo
3           Baz

Update

Foo / company_id = 1 does not have a company-level note because the note also has a location_id , which makes it a location-level note. Company-level notes are notes that only link to a company (and not a location).

End of Update

I've tried doing something like this, but it returns an empty set, so I'm not sure if it's working and there aren't any companies without company-level notes or if I'm doing something wrong.

SELECT DISTINCT 
c.company_id, 
c.name
FROM company AS c
LEFT JOIN note AS n
ON c.company_id = n.company_id
WHERE 
c.deleted = 0 AND
n.deleted = 0 AND
n.location_id IS NOT NULL AND 
n.location_id != 0 AND
c.company_id = (SELECT MAX(company_id) FROM company)

Revised Accepted Answer by Mike

SELECT
    company_id,
    name
FROM company
WHERE 
    deleted = 0 AND
    company_id NOT IN (
        SELECT DISTINCT 
            c.company_id
        FROM company AS c 
        INNER JOIN note AS n 
        ON c.company_id = n.company_id 
        WHERE (
            n.deleted = 0 AND
                (n.location_id IS NULL OR 
                n.location_id = 0)
        )
    );

Answer 1

The easiest way to think about this is to first find the all the companies that have company level notes, which you can do with

 select distinct c.company_id
   from company c 
 inner join notes n 
     on c.company_id = n.company_id 
  where n.location_id is null;

Then simply remove these companies from the company select:

select company_id,
       name
  from company
 where company_id not in (select distinct c.company_id
                            from company c 
                          inner join notes n 
                              on c.company_id = n.company_id 
                           where n.location_id is null);

*Updated to use inner join instead of comma-separated join.

Answer 2

SELECT DISTINCT c.* 
  FROM company c 
  LEFT 
  JOIN note n 
    ON n.company_id = c.company_id 
   AND n.location_id IS NULL 
 WHERE n.note_id IS NULL;