Documentation Home
MySQL 8.0 Reference Manual
Related Documentation Download this Manual
PDF (US Ltr) - 46.1Mb
PDF (A4) - 46.1Mb
PDF (RPM) - 41.5Mb
HTML Download (TGZ) - 10.6Mb
HTML Download (Zip) - 10.6Mb
HTML Download (RPM) - 9.1Mb
Man Pages (TGZ) - 220.4Kb
Man Pages (Zip) - 325.8Kb
Info (Gzip) - 4.1Mb
Info (Zip) - 4.1Mb
Excerpts from this Manual

MySQL 8.0 Reference Manual  /  ...  /  The INFORMATION_SCHEMA INNODB_FOREIGN Table

25.39.11 The INFORMATION_SCHEMA INNODB_FOREIGN Table

The INNODB_FOREIGN table provides metadata about InnoDB foreign keys.

For related usage information and examples, see Section 15.14.3, “InnoDB INFORMATION_SCHEMA Schema Object Tables”.

The INNODB_FOREIGN table has these columns:

  • ID

    The name (not a numeric value) of the foreign key index, preceded by the schema (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. 0 = ON DELETE/UPDATE RESTRICT, 1 = ON DELETE CASCADE, 2 = ON DELETE 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_FOREIGN\G
*************************** 1. row ***************************
      ID: test/fk1
FOR_NAME: test/child
REF_NAME: test/parent
  N_COLS: 1
    TYPE: 1

Notes

  • You must have the PROCESS privilege to query this table.

  • Use the INFORMATION_SCHEMA COLUMNS table or the SHOW COLUMNS statement to view additional information about the columns of this table, including data types and default values.