Oracle get foreign keys

Question

I\'d like to get all foreign keys in a schema, like this. Let\'s say I have tables

users(id, username, pass, address_id)

and

addr

Answer 1

Using @maephisto solution will case a little bug:
If the source tables primary key is a composite key then running the query will result duplicate unnecessary records.

Consider T1 and T2 tables:
Master table T1:

create table T1
(
  pk1 NUMBER not null,
  pk2 NUMBER not null
);
alter table T1
  add constraint T1PK primary key (PK1, PK2);

Detail table T2:

create table T2
(
  pk1   NUMBER,
  pk2   NUMBER,
  name1 VARCHAR2(100)
);
alter table T2
  add constraint T2FK foreign key (PK1, PK2)
  references T1 (PK1, PK2);

The result of the @maephisto query will be:



To over come the problem the query bellow will serve:

SELECT master_table.TABLE_NAME  MASTER_TABLE_NAME,
       master_table.column_name MASTER_KEY_COLUMN,
       detail_table.TABLE_NAME  DETAIL_TABLE_NAME,
       detail_table.column_name DETAIL_COLUMN
  FROM user_constraints  constraint_info,
       user_cons_columns detail_table,
       user_cons_columns master_table
 WHERE constraint_info.constraint_name = detail_table.constraint_name
   AND constraint_info.r_constraint_name = master_table.constraint_name
   AND detail_table.POSITION = master_table.POSITION
   AND constraint_info.constraint_type = 'R'
   AND constraint_info.OWNER = 'MY_SCHEMA'