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

使用REFERENCED_TABLE_NAME并不总是有效,它可以是一个NULL值。下面的查询可以代替:

select * from INFORMATION_SCHEMA.KEY_COLUMN_USAGE where TABLE_NAME = '<table>';

其他回答

使用REFERENCED_TABLE_NAME并不总是有效,它可以是一个NULL值。下面的查询可以代替:

select * from INFORMATION_SCHEMA.KEY_COLUMN_USAGE where TABLE_NAME = '<table>';

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;

对于表格:

SELECT 
  TABLE_NAME,COLUMN_NAME,CONSTRAINT_NAME, REFERENCED_TABLE_NAME,REFERENCED_COLUMN_NAME
FROM
  INFORMATION_SCHEMA.KEY_COLUMN_USAGE
WHERE
  REFERENCED_TABLE_SCHEMA = '<database>' AND
  REFERENCED_TABLE_NAME = '<table>';

对于列:

SELECT 
  TABLE_NAME,COLUMN_NAME,CONSTRAINT_NAME, REFERENCED_TABLE_NAME,REFERENCED_COLUMN_NAME
FROM
  INFORMATION_SCHEMA.KEY_COLUMN_USAGE
WHERE
  REFERENCED_TABLE_SCHEMA = '<database>' AND
  REFERENCED_TABLE_NAME = '<table>' AND
  REFERENCED_COLUMN_NAME = '<column>';

基本上,我们用where子句中的REFERENCED_COLUMN_NAME更改了REFERENCED_TABLE_NAME。

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

如果你使用InnoDB并定义了FK,你可以查询information_schema数据库,例如:

SELECT * FROM information_schema.TABLE_CONSTRAINTS 
WHERE information_schema.TABLE_CONSTRAINTS.CONSTRAINT_TYPE = 'FOREIGN KEY' 
AND information_schema.TABLE_CONSTRAINTS.TABLE_SCHEMA = 'myschema'
AND information_schema.TABLE_CONSTRAINTS.TABLE_NAME = 'mytable';