28.3.25 INFORMATION_SCHEMA REFERENTIAL_CONSTRAINTS 表
The REFERENTIAL_CONSTRAINTS
table provides information about foreign keys.
The REFERENTIAL_CONSTRAINTS
table has these columns:
-
CONSTRAINT_CATALOG
The name of the catalog to which the constraint belongs. This value is always
def
. -
CONSTRAINT_SCHEMA
The name of the schema (database) to which the constraint belongs.
-
CONSTRAINT_NAME
The name of the constraint.
-
UNIQUE_CONSTRAINT_CATALOG
The name of the catalog containing the unique constraint that the constraint references. This value is always
def
. -
UNIQUE_CONSTRAINT_SCHEMA
The name of the schema containing the unique constraint that the constraint references.
-
UNIQUE_CONSTRAINT_NAME
The name of the unique constraint that the constraint references.
-
MATCH_OPTION
The value of the constraint
MATCH
attribute. The only valid value at this time isNONE
. -
UPDATE_RULE
The value of the constraint
ON UPDATE
attribute. The possible values areCASCADE
,SET NULL
,SET DEFAULT
,RESTRICT
,NO ACTION
. -
DELETE_RULE
The value of the constraint
ON DELETE
attribute. The possible values areCASCADE
,SET NULL
,SET DEFAULT
,RESTRICT
,NO ACTION
. -
TABLE_NAME
The name of the table. This value is the same as in the
TABLE_CONSTRAINTS
table. -
REFERENCED_TABLE_NAME
The name of the table referenced by the constraint.