在MySQL中,如何获得所有外键约束指向特定表的列表?一个特定的专栏?这和Oracle的问题是一样的,但是是MySQL的问题。
当前回答
作为Node的替代答案,如果你使用InnoDB并定义了FK,你可以查询information_schema数据库,例如:
SELECT CONSTRAINT_NAME, TABLE_NAME, REFERENCED_TABLE_NAME
FROM information_schema.REFERENTIAL_CONSTRAINTS
WHERE CONSTRAINT_SCHEMA = '<schema>'
AND TABLE_NAME = '<table>'
对于<表>中的外键,或
SELECT CONSTRAINT_NAME, TABLE_NAME, REFERENCED_TABLE_NAME
FROM information_schema.REFERENTIAL_CONSTRAINTS
WHERE CONSTRAINT_SCHEMA = '<schema>'
AND REFERENCED_TABLE_NAME = '<table>'
对于<表>的外键
如果需要,还可以获得UPDATE_RULE和DELETE_RULE。
其他回答
作为Node的替代答案,如果你使用InnoDB并定义了FK,你可以查询information_schema数据库,例如:
SELECT CONSTRAINT_NAME, TABLE_NAME, REFERENCED_TABLE_NAME
FROM information_schema.REFERENTIAL_CONSTRAINTS
WHERE CONSTRAINT_SCHEMA = '<schema>'
AND TABLE_NAME = '<table>'
对于<表>中的外键,或
SELECT CONSTRAINT_NAME, TABLE_NAME, REFERENCED_TABLE_NAME
FROM information_schema.REFERENTIAL_CONSTRAINTS
WHERE CONSTRAINT_SCHEMA = '<schema>'
AND REFERENCED_TABLE_NAME = '<table>'
对于<表>的外键
如果需要,还可以获得UPDATE_RULE和DELETE_RULE。
在旧的答案上添加一些有用的信息。
我遇到了类似的问题,但我还想查看CONSTRAINT_TYPE以及引用的表和列名。所以,
To see all FKs in your table: USE '<yourschema>'; SELECT i.TABLE_NAME, i.CONSTRAINT_TYPE, i.CONSTRAINT_NAME, k.REFERENCED_TABLE_NAME, k.REFERENCED_COLUMN_NAME FROM information_schema.TABLE_CONSTRAINTS i LEFT JOIN information_schema.KEY_COLUMN_USAGE k ON i.CONSTRAINT_NAME = k.CONSTRAINT_NAME WHERE i.CONSTRAINT_TYPE = 'FOREIGN KEY' AND i.TABLE_SCHEMA = DATABASE() AND i.TABLE_NAME = '<yourtable>'; To see all the tables and FKs in your schema: USE '<yourschema>'; SELECT i.TABLE_NAME, i.CONSTRAINT_TYPE, i.CONSTRAINT_NAME, k.REFERENCED_TABLE_NAME, k.REFERENCED_COLUMN_NAME FROM information_schema.TABLE_CONSTRAINTS i LEFT JOIN information_schema.KEY_COLUMN_USAGE k ON i.CONSTRAINT_NAME = k.CONSTRAINT_NAME WHERE i.CONSTRAINT_TYPE = 'FOREIGN KEY' AND i.TABLE_SCHEMA = DATABASE(); To see all the FKs in your database: SELECT i.TABLE_SCHEMA, i.TABLE_NAME, i.CONSTRAINT_TYPE, i.CONSTRAINT_NAME, k.REFERENCED_TABLE_NAME, k.REFERENCED_COLUMN_NAME FROM information_schema.TABLE_CONSTRAINTS i LEFT JOIN information_schema.KEY_COLUMN_USAGE k ON i.CONSTRAINT_NAME = k.CONSTRAINT_NAME WHERE i.CONSTRAINT_TYPE = 'FOREIGN KEY';
记住!
这里使用的是InnoDB存储引擎。如果在添加外键后,似乎无法显示任何外键,这可能是因为您的表正在使用MyISAM。
检查:
SELECT * TABLE_NAME, ENGINE FROM information_schema.TABLES WHERE TABLE_SCHEMA = '<yourschema>';
要修复,使用这个:
ALTER TABLE `<yourtable>` ENGINE=InnoDB;
这个解决方案不仅会显示所有的关系,还会显示约束的名称,这在某些情况下是必需的(例如drop constraint):
select
concat(table_name, '.', column_name) as 'foreign key',
concat(referenced_table_name, '.', referenced_column_name) as 'references',
constraint_name as 'constraint name'
from
information_schema.key_column_usage
where
referenced_table_name is not null;
如果你想检查特定数据库中的表,在查询的最后添加模式名:
select
concat(table_name, '.', column_name) as 'foreign key',
concat(referenced_table_name, '.', referenced_column_name) as 'references',
constraint_name as 'constraint name'
from
information_schema.key_column_usage
where
referenced_table_name is not null
and table_schema = 'database_name';
同样,对于特定的列名,添加
table_name = 'table_name
在查询的末尾。
受到这篇文章的启发
方法列出fk(外键引用)的快速方法
KEY_COLUMN_USAGE view:
SELECT CONCAT( table_name, '.',
column_name, ' -> ',
referenced_table_name, '.',
referenced_column_name ) AS list_of_fks
FROM information_schema.KEY_COLUMN_USAGE
WHERE REFERENCED_TABLE_SCHEMA = (your schema name here)
AND REFERENCED_TABLE_NAME is not null
ORDER BY TABLE_NAME, COLUMN_NAME;
这个查询假设约束和所有引用和引用的表都在同一个模式中。
添加你自己的评论。
来源:mysql官方手册。
我提出的解决方案是脆弱的;它依赖于django的外键命名约定。
USE information_schema;
tee mysql_output
SELECT * FROM TABLE_CONSTRAINTS WHERE CONSTRAINT_TYPE = 'FOREIGN KEY' AND TABLE_SCHEMA = 'database_name';
notee
然后在壳层中,
grep 'refs_tablename_id' mysql_output