hi everyone, i am trying to compare 2 tables and return the difference, i can join the tables (no problem there), but can`t get the difference in the 2. to clarify my problem, table1 has company_id as does table2 but table 2 does not have ALL the company_id`s as table 1 has, now i am wanting to find out the company_id`s that do not match. this is what i am currently trying, i am not getting any errors, all i am getting is the company_id`s that DO match.
$query=mysql_query("SELECT * from company as c1
messages as c2
on c1.company_id=c2.company_id where c1.company_id != ''") or die (mysql_error());