Information Schema INNODB_SYS_FOREIGN Table
The Information Schema INNODB_SYS_FOREIGN table contains information about InnoDB foreign keys.
The PROCESS privilege is required to view the table.
It has the following columns:
| Column | Description |
|---|---|
ID |
Database name and foreign key name. |
FOR_NAME |
Database and table name of the foreign key child. |
REF_NAME |
Database and table name of the foreign key parent. |
N_COLS |
Number of foreign key index columns. |
TYPE |
Bit flag providing information about the foreign key. |
The TYPE column provides a bit flag with information about the foreign key. This information is OR'ed together to read:
| Bit Flag | Description |
|---|---|
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
SELECT * FROM INNODB_SYS_FOREIGN\G
*************************** 1. row ***************************
ID: mysql/innodb_index_stats_ibfk_1
FOR_NAME: mysql/innodb_index_stats
REF_NAME: mysql/innodb_table_stats
N_COLS: 2
TYPE: 0
...
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https://mariadb.com/kb/en/information-schema-innodb_sys_foreign-table/