The INNODB_SYS_FOREIGN table provides metadata
about InnoDB
foreign keys, equivalent
to the information from the SYS_FOREIGN table
in the InnoDB data dictionary.
For related usage information and examples, see Section 14.15.3, “InnoDB INFORMATION_SCHEMA System Tables”.
Table 21.19 INNODB_SYS_FOREIGN Columns
| Column name | Description |
|---|---|
ID | The name (not a numeric value) of the foreign key index. Preceded by the
database name, for example,
test/products_fk. |
FOR_NAME | The name of the child table in this foreign key relationship. |
REF_NAME | The name of the parent table in this foreign key relationship. |
N_COLS | The number of columns in the foreign key index. |
TYPE | A collection of bit flags with information about the foreign key column,
ORed together. 1 = ON DELETE CASCADE, 2
= ON UPDATE SET NULL, 4 = ON
UPDATE CASCADE, 8 = ON UPDATE
SET NULL, 16 = ON DELETE NO
ACTION, 32 = ON UPDATE NO ACTION. |
Example:
mysql> SELECT * FROM INFORMATION_SCHEMA.INNODB_SYS_FOREIGN\G
*************************** 1. row ***************************
ID: test/fk1
FOR_NAME: test/child
REF_NAME: test/parent
N_COLS: 1
TYPE: 1
Notes:
Use DESCRIBE or
SHOW COLUMNS to view additional
information about the columns of this table including data
types and default values.
You must have the PROCESS
privilege to query this table.