Query a Table's Foreign Key relationships

Question

For a given table 'foo', I need a query to generate a set of tables that have foreign keys that point to foo. I'm using Oracle 10G.

Answer 1

This should work (or something close):

select table_name
from all_constraints
where constraint_type='R'
and r_constraint_name in 
  (select constraint_name
  from all_constraints
  where constraint_type in ('P','U')
  and table_name='<your table here>'); 

Answer 2

The following statement should give the children and all of their descendents. I have tested it on an Oracle 10 database.

SELECT  level, main.table_name  parent,
    link.table_name child
FROM    user_constraints main, user_constraints link    
WHERE   main.constraint_type    IN ('P', 'U')
AND link.r_constraint_name  = main.constraint_name
START WITH main.table_name  LIKE UPPER('&&table_name')
CONNECT BY main.table_name = PRIOR link.table_name
ORDER BY level, main.table_name, link.table_name

Answer 3

Here's how to take Mike's query one step further to get the column names from the constraint names:

select * from user_cons_columns
where constraint_name in (
  select constraint_name 
  from all_constraints
  where constraint_type='R'
  and r_constraint_name in 
    (select constraint_name
    from all_constraints
    where constraint_type in ('P','U')
    and table_name='<your table name here>'));

Answer 4

link to Oracle Database Online Documentation

You may want to explore the Data Dictionary views. They have the prefixes:

• User
• All
• DBA

sample:

select * from dictionary where table_name like 'ALL%' 

---

Continuing Mike's example, you may want to generate scripts to enable/disable the constraints. I only modified the 'select' in the first row.

select  'alter table ' || TABLE_NAME || ' disable constraint ' || CONSTRAINT_NAME || ';'
from all_constraints
where constraint_type='R'
and r_constraint_name in 
  (select constraint_name
  from all_constraints
  where constraint_type in ('P','U')
  and table_name='<your table here>');

Answer 5

I know it's kinda late to answer but let me answer anyway. Some of the answers above are quite complicated hence here is a much simpler take.

SELECT a.table_name child_table, a.column_name child_column, a.constraint_name, 
b.table_name parent_table, b.column_name parent_column
FROM all_cons_columns a
JOIN all_constraints c ON a.owner = c.owner AND a.constraint_name = c.constraint_name
join all_cons_columns b on c.owner = b.owner and c.r_constraint_name = b.constraint_name
WHERE c.constraint_type = 'R'
AND a.table_name = 'your table name'

Answer 6

select distinct table_name, constraint_name, column_name, r_table_name, position, constraint_type 
from (
    SELECT uc.table_name, 
    uc.constraint_name, 
    cols.column_name, 
    (select table_name from user_constraints where constraint_name = uc.r_constraint_name) 
        r_table_name,
    (select column_name from user_cons_columns where constraint_name = uc.r_constraint_name and position = cols.position) 
        r_column_name,
    cols.position,
    uc.constraint_type
    FROM user_constraints uc
    inner join user_cons_columns cols on uc.constraint_name = cols.constraint_name 
    where constraint_type != 'C'
) 
start with table_name = '&&tableName' and column_name = '&&columnName'  
connect by nocycle 
prior table_name = r_table_name 
and prior column_name = r_column_name;   

Answer 7

Download the Oracle Reference Guide for 10G which explains the data dictionary tables.

The answers above are good but check out the other tables which may relate to constraints.

SELECT * FROM DICT WHERE TABLE_NAME LIKE '%CONS%';

Finally, get a tool like Toad or SQL Developer which allows you to browse this stuff in a UI, you need to learn to use the tables but you should use a UI also.

Answer 8

select      acc.table_name, acc.constraint_name 
from        all_cons_columns acc
inner join all_constraints ac
    on acc.constraint_name = ac.constraint_name
where       ac.r_constraint_name in (
    select  constraint_name
    from    all_constraints
    where   table_name='yourTable'
    );

Answer 9

All constraints for one table

select 

    uc.OWNER,
    uc.constraint_name as TableConstraint1,
    uc.r_constraint_name as TableConstraint2,
    uc.constraint_type as constrainttype1,
    us.constraint_type as constrainttype2,
    uc.table_name as Table1,us.table_name as Table2,
    ucc.column_name as TableColumn1, 
    uccs.column_name as TableColumn2
from user_constraints uc
    left outer join user_constraints us on uc.r_constraint_name = us.constraint_name
    left outer join USER_CONS_COLUMNS ucc on ucc.constraint_name = uc.constraint_name
    left outer join USER_CONS_COLUMNS uccs on uccs.constraint_name = us.constraint_name
where uc.OWNER ='xxxx' and uc.table_name='xxxx' 

Answer 10

Adding my two cents here.

This query will return all foreign keys with child and parent columns, matched perfectly even when there is foreign key over multiple columns:

SELECT a.table_name child_table, a.column_name child_column, a.constraint_name, 
b.table_name parent_table, b.column_name parent_column
FROM all_cons_columns a
JOIN all_constraints c ON a.owner = c.owner AND a.constraint_name = c.constraint_name
JOIN all_cons_columns b ON c.owner = b.owner AND c.r_constraint_name = b.constraint_name AND b.position = a.position
WHERE c.constraint_type = 'R'

(inspired by @arvinq aswer)