MySQL 8.4 Release Notes
INNODB_FOREIGN 表提供有关 InnoDB 外键 的元数据。The INNODB_FOREIGN table provides
metadata about InnoDB
foreign keys.
有关相关的使用信息和示例，请参见 第 17.15.3 节，“InnoDB INFORMATION_SCHEMA 模式对象表”。For related usage information and examples, see Section 17.15.3, “InnoDB INFORMATION_SCHEMA Schema Object Tables”.
INNODB_FOREIGN 表具有以下列：The INNODB_FOREIGN table has these
columns:
ID外键索引的名称（不是数字值），前面加上模式（数据库）名称（例如
test/products_fk）。The name (not a numeric value) of the foreign key index, preceded by the schema (database) name (for example,test/products_fk).FOR_NAME此外键关系中 子表 的名称。The name of the child table in this foreign key relationship.
REF_NAME在此外键关系中 父表 的名称。The name of the parent table in this foreign key relationship.
N_COLS外键索引中的列数。The number of columns in the foreign key index.
TYPETYPE包含有关外键列信息的一组位标志，按位或组合。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。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.
示例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
注释Notes
你必须拥有
PROCESS权限才能查询此表。You must have thePROCESSprivilege to query this table.使用
INFORMATION_SCHEMACOLUMNS表或SHOW COLUMNS语句查看关于此表列的更多信息，包括数据类型和默认值。Use theINFORMATION_SCHEMACOLUMNStable or theSHOW COLUMNSstatement to view additional information about the columns of this table, including data types and default values.