REFERENTIAL_CONSTRAINTS表提供有关外键的信息。
REFERENTIAL_CONSTRAINTS有以下列：
CONSTRAINT_CATALOG ：约束所属目录的名称。该值始终为def。CONSTRAINT_SCHEMA ：约束所属schema（database）的名称CONSTRAINT_NAME ：约束名称UNIQUE_CONSTRAINT_CATALOG：包含约束引用的唯一约束的目录的名称。该值始终为def。UNIQUE_CONSTRAINT_SCHEMA ：包含约束引用的唯一约束的schema（数据库）的名称。UNIQUE_CONSTRAINT_NAME ：约束引用的唯一约束的名称。MATCH_OPTION ：约束MATCH属性的值。此时唯一有效的值是NONE。UPDATE_RULE ：约束ON UPDATE属性的值。可能的值是CASCADE，SET NULL，SET DEFAULT，RESTRICT，NO ACTION。DELETE_RULE ：约束ON DELETE属性的值。可能的值是CASCADE，SET NULL，SET DEFAULT，RESTRICT，NO ACTION。TABLE_NAME ：表的名称。此值与TABLE_CONSTRAINTS表中的值相同。REFERENCED_TABLE_NAME ：约束引用的表的名称。示例
mysql> select * from REFERENTIAL_CONSTRAINTS; +--------------------+-------------------+-----------------+---------------------------+--------------------------+------------------------+--------------+-------------+-------------+------------+-----------------------+ | CONSTRAINT_CATALOG | CONSTRAINT_SCHEMA | CONSTRAINT_NAME | UNIQUE_CONSTRAINT_CATALOG | UNIQUE_CONSTRAINT_SCHEMA | UNIQUE_CONSTRAINT_NAME | MATCH_OPTION | UPDATE_RULE | DELETE_RULE | TABLE_NAME | REFERENCED_TABLE_NAME | +--------------------+-------------------+-----------------+---------------------------+--------------------------+------------------------+--------------+-------------+-------------+------------+-----------------------+ | def | test | CO | def | test | PRIMARY | NONE | RESTRICT | RESTRICT | t3 | t1 | +--------------------+-------------------+-----------------+---------------------------+--------------------------+------------------------+--------------+-------------+-------------+------------+-----------------------+ 1 row in set (0.02 sec)转载于:https://www.cnblogs.com/wanbin/p/9514631.html
