Question

我不明白。有人可以在这里解释我的失败：

CREATE TABLE IF NOT EXISTS `mytable`.`Employee_Service` (
  `Employee_Service_Id` INT NOT NULL,
  `Created_At` TIMESTAMP NULL DEFAULT CURRENT_TIMESTAMP,
  `Updated_At` TIMESTAMP NULL,
  PRIMARY KEY (`Employee_Service_Id`),
  CONSTRAINT `Employee`
    FOREIGN KEY (`Employee_Service_Id`)
    REFERENCES `mytable`.`Employees` (`Employee_Id`)
    ON DELETE NO ACTION
    ON UPDATE NO ACTION,
  CONSTRAINT `Service`
    FOREIGN KEY (`Employee_Service_Id`)
    REFERENCES `mytable`.`Services` (`Service_Id`)
    ON DELETE NO ACTION
    ON UPDATE NO ACTION)
ENGINE = InnoDB

日志文件说：

Error 1022: Can't write; duplicate key in table 'employee_service'

要了解我想用它做什么：表＆＃34; Employee_Service＆＃34;表格和＃34;员工之间的联系＆＃34;和＆＃34;服务＆＃34;。在该表中，我想存储＆＃34; Employee_Id＆＃34;从表格＆＃34;员工＆＃34;并将其与＆＃34; Service_Id＆＃34;从表格＆＃34;服务＆＃34;。所以我可以得到员工有服务的关系。但是我的桌子出了什么问题，尤其是外出钥匙???

Answer 1

很可能您的其他表具有名为Employee和Service的相同约束。您发布的CREATE语句的另一个问题是，您尝试将Employee_Service_Id同为PK和FK

PRIMARY KEY (`Employee_Service_Id`),
  CONSTRAINT `Employee`
    FOREIGN KEY (`Employee_Service_Id`)

mysql无法写 - 重复密钥

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