Question

如果我有：

create table order_items
( 
  orderid int unsigned not null references orders(orderid),
  isbn char(13) not null,
  quantity tinyint unsigned,

  primary key (orderid, isbn)

);

如何查看是否存在orderid int unsigned not null references orders(orderid)外键？

Answer 1

您可以像这样使用INFORMATION_SCHEMA.REFERENTIAL_CONSTRAINTS：

SELECT *
FROM information_schema.REFERENTIAL_CONSTRAINTS
WHERE CONSTRAINT_SCHEMA = '<schema>'
AND REFERENCED_TABLE_NAME = 'order_items'
AND CONSTRAINT_NAME = 'orderid'

Answer 2

您可以使用它来检查整个数据库中的外键约束

SELECT TABLE_NAME ,
    COLUMN_NAME,
    CONSTRAINT_NAME,
    REFERENCED_TABLE_NAME,
    REFERENCED_COLUMN_NAME
FROM
    INFORMATION_SCHEMA.KEY_COLUMN_USAGE

需要检查特定表意味着请在上面的查询中的条件中添加此

WHERE
    REFERENCED_TABLE_SCHEMA = 'student' AND REFERENCED_TABLE_NAME = 'student_details'

MySql检查是否存在外键约束

2 个答案: