I have a table called 'countries' linked to another table 'networks' with a many to many relationship:

  countries             countries_networks                networks
+-------------+----------+  +-------------+----------+  +-------------+---------------+
| Field       | Type     |  | Field       | Type     |  | Field       | Type          |
+-------------+----------+  +-------------+----------+  +-------------+---------------+  
| id          | int(11)  |  | id          | int(11)  |  | id          | int(11)       |
| countryName | char(35) |  | country_id  | int(11)  |  | name        | varchar(100)  |
+-------------+----------+  | network_id  | int(11)  |  | description | varchar(255)  |

To retrieve all countries that have a network_id of 6 & 7, I just do the following: ( I could go further to use the networks.name but I know the countries_networks.network_id so i just use those to reduce SQL.)

SELECT DISTINCT countryName 
 FROM countries AS Country
INNER JOIN countries_networks AS n ON Country.id = n.country_id
 WHERE n.network_id IN (6,7)

This is fine, but I then want to retrieve the countries with a network_id of JUST 8, and no others.

I'ver tried the following but its still returning networks with 6 & 7 in. Is it something to do with my JOIN?

SELECT DISTINCT countryName 
 FROM countries AS Country
INNER JOIN countries_networks AS n ON Country.id = n.country_id
 WHERE n.network_id IN (8)
AND n.network_id not IN(6,7)

Thanks.