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25.39.11 The INFORMATION_SCHEMA INNODB_FOREIGN Table

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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

  1. mysql> SELECT * FROM INFORMATION_SCHEMA.INNODB_FOREIGN\G
  2. *************************** 1. row ***************************
  3.       ID: test/fk1
  4. FOR_NAME: test/child
  5. REF_NAME: test/parent
  6.   N_COLS: 1
  7.     TYPE: 1

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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.


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Document created the 26/06/2006, last modified the 26/10/2018
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