mysql主外键依赖关系
查看主外键的依赖关系：
在oracle中可以通过DBA_DEPENDENCIES查看得到。 在mysql中也可以查看
通过查看 information_schema. key_column_usage
MariaDB [test]> create table t1 ( id int primary key,name varchar(10));
Query OK, 0 rows affected (0.36 sec)
MariaDB [test]> create table t2 (id int,score int);
Query OK, 0 rows affected (0.04 sec)
MariaDB [test]> Alter table t2 add foreign key (id) references t1(id);
Query OK, 0 rows affected (0.15 sec)
Records: 0 Duplicates: 0 Warnings: 0
MariaDB [test]> show create table t2;
+-------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table | Create Table |
+-------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| t2 | CREATE TABLE `t2` (
`id` int(11) DEFAULT NULL,
`score` int(11) DEFAULT NULL,
KEY `id` (`id`),
CONSTRAINT `t2_ibfk_1` FOREIGN KEY (`id`) REFERENCES `t1` (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_swedish_ci |
+-------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)
MariaDB [information_schema]> select * from key_column_usage where
-> REFERENCED_COLUMN_NAME='ID' and
-> REFERENCED_TABLE_NAME='T1'
-> ;
+--------------------+-------------------+-----------------+---------------+--------------+------------+-------------+------------------+-------------------------------+-------------------------+-----------------------+------------------------+
| CONSTRAINT_CATALOG | CONSTRAINT_SCHEMA | CONSTRAINT_NAME | TABLE_CATALOG | TABLE_SCHEMA | TABLE_NAME | COLUMN_NAME | ORDINAL_POSITION | POSITION_IN_UNIQUE_CONSTRAINT | REFERENCED_TABLE_SCHEMA | REFERENCED_TABLE_NAME | REFERENCED_COLUMN_NAME |
+--------------------+-------------------+-----------------+---------------+--------------+------------+-------------+------------------+-------------------------------+-------------------------+-----------------------+------------------------+
| def | test | t2_ibfk_1 | def | test | t2 | id | 1 | 1 | test | t1 | id |
+--------------------+-------------------+-----------------+---------------+--------------+------------+-------------+------------------+-------------------------------+-------------------------+-----------------------+------------------------+
1 row in set (0.01 sec)
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