强制外键约束到同一个表的列 [英] Enforce a foreign-key constraint to columns of same table

问题描述

如何在SQL中的同一表的列上强制执行外键约束，同时在下表中输入值：

员工：

• empid号码，


• 经理号码（必须是现有员工）$ （
  `empid_number` int（
  ``empid_number`）（
  `````````````` 11）NOT NULL auto_increment，
  `employee` varchar（100）NOT NULL，
  `manager_number` int（11）NOT NULL，
  PRIMARY KEY（`empid_number`），
  CONSTRAINT`manager_references_employee`
  FOREIGN KEY（`manager_number`）REFERENCES（`empid_number`）
  ）ENGINE = InnoDB DEFAULT CHARSET = utf8
  

  希望它有帮助！

  
  

  How to enforce a constraint of foreign key on columns of same table in SQL while entering values in the following table:

  employee:

  • empid number,
  • manager number (must be an existing employee)

  解决方案

  CREATE TABLE TABLE_NAME (
      `empid_number`    int     (  11) NOT NULL auto_increment,   
      `employee`        varchar ( 100) NOT NULL               ,
      `manager_number`  int     (  11) NOT NULL               ,
       PRIMARY KEY  (`empid_number`),
       CONSTRAINT `manager_references_employee`
       FOREIGN KEY (`manager_number`) REFERENCES (`empid_number`)
  ) ENGINE=InnoDB DEFAULT CHARSET=utf8
  

  Hope it helps!

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