Pull unique records from mysql where pageID 3 exists only

I have many ClientIDs to many pageids

Eg.

ClientID 1 PageID 3
ClientID 1 PageID 2
ClientID 2 PageID 3
ClientID 3 PageID 3

In a query I want to bring up the record with only PageID 3 exclusively.

So in my result i should get Client 2 and 3 and client 1 should be omitted out of the results... Whats the best way to do this?

If a client appears in more than one Page then there should be more than one row containing the clientId

SELECT * FROM tableName WHERE PageID = 3 GROUP BY ClientID HAVING ( COUNT(ClientID) = 1 )

I have not tested this but should work.

EDIT :

 SELECT * FROM tableName WHERE ClientID IN (SELECT ClientID FROM tableName GROUP BY ClientID HAVING (COUNT(ClientID) = 1)) AND PageID = 3

This one is tested. The previous one does not give exclusive records.

SELECT * FROM yourTableName WHERE PageID = 3

Note by your example this gets ClientID of 1, 2, 3. However, you mentioned just wanting ClientID 2, 3.