MYSQL錯誤：錯誤1215：無法添加外鍵約束

Question

我試圖將我的ERD向前工程到Workbench 6.0中的方案中，但出現此錯誤。 我檢查了所有列類型，它們是相同的。 我在這里瀏覽了類似的問題，但仍然找不到答案。 這是錯誤日志：

xecuting SQL script in server

ERROR: Error 1215: Cannot add foreign key constraint







-- -----------------------------------------------------

-- Table `proj`.`employee`

-- -----------------------------------------------------

CREATE TABLE IF NOT EXISTS `proj`.`employee` (

  `employee_id` INT NOT NULL,

  `position_id` INT NOT NULL,

  PRIMARY KEY (`employee_id`),

  CONSTRAINT `fk_employee_employee_history1`

    FOREIGN KEY (`employee_id`)

    REFERENCES `proj`.`employee_history` (`employee_id`)

    ON DELETE NO ACTION

    ON UPDATE NO ACTION,

  CONSTRAINT `fk_employee_equipment_rentals1`

    FOREIGN KEY (`employee_id`)

    REFERENCES `proj`.`equipment_rentals` (`handling_employee_id`)

    ON DELETE NO ACTION

    ON UPDATE NO ACTION,

  CONSTRAINT `fk_employee_scheduled_trips1`

    FOREIGN KEY (`employee_id`)

    REFERENCES `proj`.`scheduled_trips` (`leader`)

    ON DELETE NO ACTION

    ON UPDATE NO ACTION,

  CONSTRAINT `fk_employee_scheduled_trips2`

    FOREIGN KEY (`employee_id`)

    REFERENCES `proj`.`scheduled_trips` (`assistant`)

    ON DELETE NO ACTION

    ON UPDATE NO ACTION)

ENGINE = InnoDB



SQL script execution finished: statements: 8 succeeded, 1 failed



Fetching back view definitions in final form.

Nothing to fetch

Answer 1

原來我的外鍵約束都搞砸了。 我的關系倒退了。 我不是讓外鍵引用主鍵，而是讓主鍵成為引用非唯一列的外鍵。 我扭轉了這一點，並且奏效了。