REFERENTIAL_CONSTRAINTS

REFERENTIAL_CONSTRAINTS 表提供 TiDB 表之间 FOREIGN KEY 关系的信息。请注意,目前 TiDB 不强制进行 FOREIGN KEY 约束,也不执行 ON DELETE CASCADE 等操作。

USE information_schema; DESC referential_constraints;
+---------------------------+--------------+------+------+---------+-------+ | Field | Type | Null | Key | Default | Extra | +---------------------------+--------------+------+------+---------+-------+ | CONSTRAINT_CATALOG | varchar(512) | NO | | NULL | | | CONSTRAINT_SCHEMA | varchar(64) | NO | | NULL | | | CONSTRAINT_NAME | varchar(64) | NO | | NULL | | | UNIQUE_CONSTRAINT_CATALOG | varchar(512) | NO | | NULL | | | UNIQUE_CONSTRAINT_SCHEMA | varchar(64) | NO | | NULL | | | UNIQUE_CONSTRAINT_NAME | varchar(64) | YES | | NULL | | | MATCH_OPTION | varchar(64) | NO | | NULL | | | UPDATE_RULE | varchar(64) | NO | | NULL | | | DELETE_RULE | varchar(64) | NO | | NULL | | | TABLE_NAME | varchar(64) | NO | | NULL | | | REFERENCED_TABLE_NAME | varchar(64) | NO | | NULL | | +---------------------------+--------------+------+------+---------+-------+ 11 rows in set (0.00 sec)
CREATE TABLE test.parent ( id INT NOT NULL AUTO_INCREMENT, PRIMARY KEY (id) ); CREATE TABLE test.child ( id INT NOT NULL AUTO_INCREMENT, name varchar(255) NOT NULL, parent_id INT DEFAULT NULL, PRIMARY KEY (id), CONSTRAINT fk_parent FOREIGN KEY (parent_id) REFERENCES parent (id) ON UPDATE CASCADE ON DELETE RESTRICT ); SELECT * FROM referential_constraints\G
*************************** 1. row *************************** CONSTRAINT_CATALOG: def CONSTRAINT_SCHEMA: test CONSTRAINT_NAME: fk_parent UNIQUE_CONSTRAINT_CATALOG: def UNIQUE_CONSTRAINT_SCHEMA: test UNIQUE_CONSTRAINT_NAME: PRIMARY MATCH_OPTION: NONE UPDATE_RULE: CASCADE DELETE_RULE: RESTRICT TABLE_NAME: child REFERENCED_TABLE_NAME: parent 1 row in set (0.00 sec)
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