Information Schema REFERENTIAL_CONSTRAINTS Table

The Information Schema REFERENTIAL_CONSTRAINTS table contains metadata about foreign keys, including update and delete rules.

The Information Schema REFERENTIAL_CONSTRAINTS table contains information about foreign keys. The single columns are listed in the KEY_COLUMN_USAGE table.

It has the following columns:

Column	Description
CONSTRAINT_CATALOG	Always def.
CONSTRAINT_SCHEMA	Database name, together with CONSTRAINT_NAME identifies the foreign key.
CONSTRAINT_NAME	Foreign key name, together with CONSTRAINT_SCHEMA identifies the foreign key.
UNIQUE_CONSTRAINT_CATALOG	Always def.
UNIQUE_CONSTRAINT_SCHEMA	Database name, together with UNIQUE_CONSTRAINT_NAME and REFERENCED_TABLE_NAME identifies the referenced key.
UNIQUE_CONSTRAINT_NAME	Referenced key name, together with UNIQUE_CONSTRAINT_SCHEMA and REFERENCED_TABLE_NAME identifies the referenced key.
MATCH_OPTION	Always NONE.
UPDATE_RULE	The Update Rule; one of CASCADE, SET NULL, SET DEFAULT, RESTRICT, NO ACTION.
DELETE_RULE	The Delete Rule; one of CASCADE, SET NULL, SET DEFAULT, RESTRICT, NO ACTION.
TABLE_NAME	Table name from the TABLE_CONSTRAINTS table.
REFERENCED_TABLE_NAME	Referenced key table name, together with UNIQUE_CONSTRAINT_SCHEMA and UNIQUE_CONSTRAINT_NAME identifies the referenced key.

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