REFERENTIAL_CONSTRAINTS view¶

This Information Schema view displays a row for each FOREIGN KEY constraint that is defined for tables in the specified (or current) database.

FOREIGN KEY constraints are used to enforce referential integrity. For more information, see Constraints and Referential Integrity Constraints.

To return information about other constraint types (as well as FOREIGN KEY constraints), query the TABLE_CONSTRAINTS view.

See also:: TABLE_CONSTRAINTS view

Columns¶

Column Name	Data Type	Description
CONSTRAINT_CATALOG	VARCHAR	Database that the constraint belongs to
CONSTRAINT_SCHEMA	VARCHAR	Schema that the constraint belongs to
CONSTRAINT_NAME	VARCHAR	Name of the constraint
UNIQUE_CONSTRAINT_CATALOG	VARCHAR	Database of the unique constraint referenced by the current constraint
UNIQUE_CONSTRAINT_SCHEMA	VARCHAR	Schema of the unique constraint referenced by the current constraint
UNIQUE_CONSTRAINT_NAME	VARCHAR	Name of the unique constraint referenced by the current constraint
MATCH_OPTION	VARCHAR	Match option for the constraint
UPDATE_RULE	VARCHAR	Update Rule for the current constraint
DELETE_RULE	VARCHAR	Delete Rule for the current constraint
COMMENT	VARCHAR	Comment for this constraint
CREATED	TIMESTAMP_LTZ	Creation time of the constraint
LAST_ALTERED	TIMESTAMP_LTZ	Date and time the object was last altered by a DML, DDL, or background metadata operation. See Usage Notes.

Usage notes¶

The view only displays objects for which the current role for the session has been granted access privileges.
The LAST_ALTERED column is updated when the following operations are performed on an object:
- DDL operations.
- DML operations (for tables only). This column is updated even when no rows are affected by the DML statement.
- Background maintenance operations on metadata performed by Snowflake.

Examples¶

Return information about all of the FOREIGN KEY constraints in the current database.

SELECT * FROM INFORMATION_SCHEMA.REFERENTIAL_CONSTRAINTS;

+--------------------+-------------------+-----------------------------------------------------+---------------------------+--------------------------+-----------------------------------------------------+--------------+-------------+-------------+---------+-------------------------------+-------------------------------+
| CONSTRAINT_CATALOG | CONSTRAINT_SCHEMA | CONSTRAINT_NAME                                     | UNIQUE_CONSTRAINT_CATALOG | UNIQUE_CONSTRAINT_SCHEMA | UNIQUE_CONSTRAINT_NAME                              | MATCH_OPTION | UPDATE_RULE | DELETE_RULE | COMMENT | CREATED                       | LAST_ALTERED                  |
|--------------------+-------------------+-----------------------------------------------------+---------------------------+--------------------------+-----------------------------------------------------+--------------+-------------+-------------+---------+-------------------------------+-------------------------------|
| HTABLES_DB         | HTABLES_SCHEMA    | SYS_CONSTRAINT_51118aaf-1ee6-4548-bc9a-f87e65d92528 | HTABLES_DB                | HTABLES_SCHEMA           | SYS_CONSTRAINT_aad16788-491a-4e68-b0e3-30d48a33a1c1 | FULL         | NO ACTION   | NO ACTION   | NULL    | 2024-09-19 13:51:37.355 -0700 | 2024-09-19 13:51:37.608 -0700 |
| HTABLES_DB         | HTABLES_SCHEMA    | SYS_CONSTRAINT_c97bfe9b-6098-4b8a-b796-e341071db72a | HTABLES_DB                | HTABLES_SCHEMA           | SYS_CONSTRAINT_0bd41d0f-11f7-4366-82a3-f03f31fcce7e | FULL         | NO ACTION   | NO ACTION   | NULL    | 2024-05-28 18:21:43.899 -0700 | 2024-05-28 18:21:44.268 -0700 |
+--------------------+-------------------+-----------------------------------------------------+---------------------------+--------------------------+-----------------------------------------------------+--------------+-------------+-------------+---------+-------------------------------+-------------------------------+

Join this view to the TABLE_CONSTRAINTS view to get the names of referencing tables that have FOREIGN KEY constraints:

SELECT tc.constraint_catalog, tc.constraint_schema, tc.constraint_name, tc.table_name, tc.constraint_type, tc.enforced
  FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS tc
    JOIN INFORMATION_SCHEMA.REFERENTIAL_CONSTRAINTS rc ON tc.constraint_name=rc.constraint_name;

+--------------------+-------------------+-----------------------------------------------------+------------+-----------------+----------+
| CONSTRAINT_CATALOG | CONSTRAINT_SCHEMA | CONSTRAINT_NAME                                     | TABLE_NAME | CONSTRAINT_TYPE | ENFORCED |
|--------------------+-------------------+-----------------------------------------------------+------------+-----------------+----------|
| HTABLES_DB         | HTABLES_SCHEMA    | SYS_CONSTRAINT_51118aaf-1ee6-4548-bc9a-f87e65d92528 | HTFK       | FOREIGN KEY     | YES      |
| HTABLES_DB         | HTABLES_SCHEMA    | SYS_CONSTRAINT_c97bfe9b-6098-4b8a-b796-e341071db72a | HT619      | FOREIGN KEY     | YES      |
+--------------------+-------------------+-----------------------------------------------------+------------+-----------------+----------+