SQL & PL/SQL :: Joins - Find Missing Records Between Two Tables?

I have two tables A with columns a.key, a.location_code, a.status and a.first_name and table B with cols b.key, b.location_code, b.status and b.first_name.

I want to find the missing records between the two tables and as well check whether each column is populated correctly. That is if u take a record with id 1 check if loc_code is same in both the tables and if they are different, insert the key and first record column and second record column into a new table. And similarly if there is no record wiht that particular id in the second table, insert the record.

For missing records in the sense for records which are present in A but not in B, am using

Select a.key_no, a.loc_code, b.loc_code
from A,B
where a.key_no=b.key_no(+)
and b.key_no IS NULL

But the problem is I need to put some constraints on the B table like b.status='Married'and b.loc_code='CA'. When am using this condition in the above query, it's throwing me error saying cannot use outer join operator in and or or.And I could not figure out how to check for the columns being populated correctly between the two tables and at the same time check for missing ones