Primary & foreign keys and the tables & columns they reference.

Referenced primary keys
Simple query that lists all primary keys and the tables & columns they use. Adjust the where clause to your needs.

Hierarchy of primary & foreign keys
A more complex query:
This will travel the hierarchy of foreign keys for a given table and column and return columns from child and grandchild, and all descendant tables.
It uses sub-queries to add r_table_name and r_column_name to user_constraints, and then uses them to connect rows.
Adjust the where clause to your needs.

Either run these as sys/system, or give the user these 2 privileges: grant select on dba_constraints to tedstruik; grant select on dba_cons_columns to tedstruik;
You can find the original queries here; I did change them quite a bit to make them more legible and to use the dba_% views:
http://stackoverflow.com/questions/1729996/list-of-foreign-keys-and-the-tables-they-reference

Region

Identification
	Sequence	10
	Title	Referenced primary keys
	Type	Report
Source
	Source Type	SQL_QUERY
	Region Source	select c.owner , c.table_name , a.column_name , a.constraint_name , c_r.owner as r_owner , c_r.table_name as r_table_name from dba_cons_columns a , dba_constraints c , dba_constraints c_r where a.constraint_name = c.constraint_name and c.r_constraint_name = c_r.constraint_name and c.constraint_type = 'R' -- # set your filters here and ( c.owner = 'TEDSTRUIK' and c.table_name = 'EMP' or c_r.owner = 'TEDSTRUIK' and c_r.table_name = 'DEPT' ) -- # order by c.owner , c.table_name , a.column_name , a.constraint_name

Region

Identification
	Sequence	20
	Title	Hierarchy of primary & foreign keys
	Type	Interactive Report
Source
	Source Type	DYNAMIC_QUERY
	Region Source	select distinct owner , table_name , constraint_type , constraint_name , position , column_name , r_owner , r_table_name from ( select uc.owner , uc.table_name , uc.constraint_name , cols.column_name , uc.r_owner , ( select table_name from dba_constraints where owner = uc.r_owner and constraint_name = uc.r_constraint_name ) as r_table_name , ( select column_name from dba_cons_columns where owner = uc.r_owner and constraint_name = uc.r_constraint_name and position = cols.position ) as r_column_name , cols.position , uc.constraint_type from dba_constraints uc , dba_cons_columns cols where uc.owner = cols.owner and uc.constraint_name = cols.constraint_name and uc.constraint_type not in ( 'C', 'U' ) -- C = check constraint, P = primary key, R = Foreign key, U = unique key and uc.table_name not like 'BIN$%' -- exclude system "tables" -- # set your filters here and uc.owner = 'TEDSTRUIK' -- # ) -- # and set the rest of your filters here -- start with table_name = 'EMP' -- and column_name = 'EMPNO' -- # connect by nocycle prior owner = r_owner and prior table_name = r_table_name and prior column_name = r_column_name order by owner , table_name , constraint_type , constraint_name , position