REFERENTIAL_CONSTRAINTS
Applies to: 
Databricks SQL Databricks Runtime 10.4 LTS and above Unity Catalog only
Preview
This feature is in Public Preview.
INFORMATION_SCHEMA.REFERENTIAL_CONSTRAINTS describes the referential integrity (RI) relationships between foreign keys and primary keys.
The rows returned are limited to constraints on the tables the user is privileged to interact with.
Definition
The REFERENTIAL_CONSTRAINTS relation contains the following columns:
| Name | Data type | Nullable | Standard | Description |
|---|---|---|---|---|
CONSTRAINT_CATALOG | STRING | No | Yes | Catalog containing the foreign key constraint. |
CONSTRAINT_SCHEMA | STRING | No | Yes | Schema containing the foreign key constraints. |
CONSTRAINT_NAME | STRING | No | Yes | Name of the check constraint. |
UNIQUE_CONSTRAINT_CATALOG | STRING | No | Yes | Catalog containing the referenced constraint. |
UNIQUE_CONSTARINT_SCHEMA | STRING | No | Yes | Schema containing the referenced constraint. |
UNIQUE_CONSTRAINT_NAME | STRING | No | Yes | Name of the referenced constraint. |
MATCH_OPTION | STRING | No | Yes | Always FULL, reserved for future use.. |
UPDATE_RULE | STRING | No | Yes | Always NO ACTION, reserved for future use. |
DELETE_RULE | STRING | No | Yes | Always NO ACTION, reserved for future use. |
Constraints
The following constraints apply to the REFERENTIAL_CONSTRAINTS relation:
| Class | Name | Column List | Description |
|---|---|---|---|
| Primary key | REF_CONS_PK | CONSTRAINT_CATALOG,CONSTRAINT_SCHEMA, CONSTRAINT_NAME | Unique identifier for the constraint. |
| Foreign key | REF_CONS_TAB_CONS_FK_FK | CONSTRAINT_CATALOG, CONSTRAINT_SCHEMA, CONSTRAINT_NAME | References TABLE_CONSTRAINTS. |
| Foreign key | REF_CONS_TAB_CONS_UC_FK | UNIQUE_CONSTRAINT_CATALOG, UNIQUE_CONSTRAINT_SCHEMA, UNIQUE_CONSTRAINT_NAME | References TABLE_CONSTRAINTS. |
Examples
SQL
> SELECT constraint_name, check_clause
FROM information_schema.referential_constraints
WHERE table_schema = 'information_schema';