Finding targeted columns in an FK - sql-server

Question

If I have a pair of SQL tables, one of these tables has a pk on one column and a unique index on another (maybe a guid and id or some other unique key).
The other table has an fk to the unique index, not the pk. Is there a way I can query information schema to find the column targeted by the fk?

Answer 1

If I get you right, you want to use metadatabase:
SELECT
K_Table = FK.TABLE_NAME,
FK_Column = CU.COLUMN_NAME,
PK_Table = PK.TABLE_NAME,
PK_Column = PT.COLUMN_NAME,
Constraint_Name = C.CONSTRAINT_NAME
FROM INFORMATION_SCHEMA.REFERENTIAL_CONSTRAINTS C
INNER JOIN INFORMATION_SCHEMA.TABLE_CONSTRAINTS FK ON C.CONSTRAINT_NAME = FK.CONSTRAINT_NAME
INNER JOIN INFORMATION_SCHEMA.TABLE_CONSTRAINTS PK ON C.UNIQUE_CONSTRAINT_NAME = PK.CONSTRAINT_NAME
INNER JOIN INFORMATION_SCHEMA.KEY_COLUMN_USAGE CU ON C.CONSTRAINT_NAME = CU.CONSTRAINT_NAME
INNER JOIN (
SELECT i1.TABLE_NAME, i2.COLUMN_NAME
FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS i1
INNER JOIN INFORMATION_SCHEMA.KEY_COLUMN_USAGE i2 ON i1.CONSTRAINT_NAME = i2.CONSTRAINT_NAME
WHERE i1.CONSTRAINT_TYPE = 'PRIMARY KEY'
) PT ON PT.TABLE_NAME = PK.TABLE_NAME
Source: http://blog.sqlauthority.com/2006/11/01/sql-server-query-to-display-foreign-key-relationships-and-name-of-the-constraint-for-each-table-in-database/

Answer 2

Try this one -
SELECT
column_name = c.name
, table_name = OBJECT_NAME(k.parent_object_id)
, referenced_column_name = rc.name
, referenced_table_name = OBJECT_NAME(k.referenced_object_id)
FROM sys.foreign_key_columns k
JOIN sys.columns c ON c.[object_id] = k.parent_object_id AND c.column_id = k.parent_column_id
JOIN sys.columns rc ON rc.[object_id] = k.referenced_object_id AND rc.column_id = k.referenced_column_id

Answer 3

select object_name(fk.REFERENCED_OBJECT_ID) object_name,
i.name index_name,
ic.index_column_id sequence,
c.name column_name
from sys.foreign_keys fk
join sys.indexes i on i.object_id = fk.REFERENCED_OBJECT_ID
and i.index_id = fk.KEY_INDEX_ID
join sys.index_columns ic on ic.object_id = fk.REFERENCED_OBJECT_ID
and ic.index_id = fk.KEY_INDEX_ID
join sys.columns c on c.object_id = fk.REFERENCED_OBJECT_ID
and c.column_id = ic.column_id
where fk.name = 'fk_tbl2_to_tbl1';
e.g.
Setup:
create table tbl1 (
a int constraint pk_tbl1 primary key,
b int constraint uq_tbl1 unique,
c int);
create table tbl2 (
b int constraint fk_tbl2_to_tbl1 references tbl1(b),
d int);
Results:
| OBJECT_NAME | INDEX_NAME | SEQUENCE | COLUMN_NAME |
-----------------------------------------------------
| tbl1 | uq_tbl1 | 1 | b |
SQL Fiddle Demo

Answer 4

--FIND COLUMNS THAT ARE PRIMARY KEY AS WELL AS FOREIGN KEY - SQL SERVER 2008
SELECT
CU.TABLE_NAME, CU.COLUMN_NAME
FROM INFORMATION_SCHEMA.KEY_COLUMN_USAGE CU
WHERE CU.CONSTRAINT_NAME IN (SELECT CONSTRAINT_NAME FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS
WHERE CONSTRAINT_TYPE = 'PRIMARY KEY') AND
COLUMN_NAME IN (SELECT COLUMN_NAME FROM INFORMATION_SCHEMA.KEY_COLUMN_USAGE
WHERE TABLE_NAME = CU.TABLE_NAME AND
COLUMN_NAME = CU.COLUMN_NAME AND
CONSTRAINT_NAME IN (SELECT CONSTRAINT_NAME FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS
WHERE CONSTRAINT_TYPE = 'FOREIGN KEY'))
Source: here