MySQL Workbench报告错误1822:未能添加外键约束。缺少约束的索引

我正在根据EER模型sql脚本创建一个mysql数据库，当尝试进行转换时（全部在mysql工作台中），我得到了上面的错误。我的目标是从附件表中的2列（从和从发送到）引用收养实体表上的收养实体id

我有两个表格，其中一个是附件：

-- -----------------------------------------------------
-- Table `afth_db`.`attachment`
-- -----------------------------------------------------
DROP TABLE IF EXISTS `afth_db`.`attachment` ;

CREATE TABLE IF NOT EXISTS `afth_db`.`attachment` (
  `attachment_id` BIGINT NOT NULL,
  `sent_from` INT NULL,
  `sent_to` INT NULL,
  `attachment_description` LONGTEXT NULL,
  `attachment_uploaded` DATETIME NULL,
  `attachment_uploaded_by` VARCHAR(255) NULL,
  `adoption_case_num` BIGINT NOT NULL,
  PRIMARY KEY (`attachment_id`),
  INDEX `fk_attachment_adoption_case1_idx` (`adoption_case_num` ASC) VISIBLE,
  UNIQUE INDEX `attachment_id_UNIQUE` (`attachment_id` ASC) VISIBLE,
  UNIQUE INDEX `adoption_case_num_UNIQUE` (`adoption_case_num` ASC) VISIBLE,
  INDEX `fk_attachment_adoption_entity1_idx` (`sent_from` ASC, `sent_to` ASC) VISIBLE,
  UNIQUE INDEX `sent_to_UNIQUE` (`sent_to` ASC) VISIBLE,
  UNIQUE INDEX `sent_from_UNIQUE` (`sent_from` ASC) VISIBLE,
  CONSTRAINT `fk_attachment_adoption_case1`
    FOREIGN KEY (`adoption_case_num`)
    REFERENCES `afth_db`.`adoption_case` (`case_num`)
    ON DELETE NO ACTION
    ON UPDATE NO ACTION,
  CONSTRAINT `fk_attachment_adoption_entity1`
    FOREIGN KEY (`sent_from` , `sent_to`)
    REFERENCES `afth_db`.`adoption_entity` (`adoption_entity_id` , `adoption_entity_id`)
    ON DELETE NO ACTION
    ON UPDATE NO ACTION)
ENGINE = InnoDB

另一个是收养实体：

-- -----------------------------------------------------
-- Table `afth_db`.`adoption_entity`
-- -----------------------------------------------------
CREATE TABLE IF NOT EXISTS `afth_db`.`adoption_entity` (
  `adoption_entity_id` INT NOT NULL,
  `adoption_entity_type` VARCHAR(255) NULL,
  PRIMARY KEY (`adoption_entity_id`),
  UNIQUE INDEX `adoption_entity_id_UNIQUE` (`adoption_entity_id` ASC) VISIBLE)
ENGINE = InnoDB

错误详细说明：

Operation failed: There was an error while applying the SQL script to the database.
ERROR 1822: Failed to add the foreign key constraint. Missing index for constraint 'fk_attachment_adoption_entity1' in the referenced table 'adoption_entity'

---

我不知道为什么它一直给我这个问题。我尝试了几种解决方案，从将类型设置为“唯一索引”、“fk_附件采用_实体1的索引”以及其他相关列，但我似乎无法消除错误。我也尝试过删除和重新创建1-1关系，但也没有帮助。有人能告诉我，我在EER模型设计中是否做错了什么吗？

您正在尝试创建一个外键引用，它跨越

实体
表中的两列
sent\u from
和
sent\u to
到单行。那不是你想要的。您希望为单个列
sent\u from
和
sent\u to
创建两个独立的外键引用。因此约束部分应如下所示：

CONSTRAINT `fk_attachment_adoption_entity_from`
    FOREIGN KEY (`sent_from`)
    REFERENCES `afth_db`.`adoption_entity` (`adoption_entity_id`)
    ON DELETE NO ACTION
    ON UPDATE NO ACTION),
CONSTRAINT `fk_attachment_adoption_entity_to`
    FOREIGN KEY (`sent_to`)
    REFERENCES `afth_db`.`adoption_entity` (`adoption_entity_id`)
    ON DELETE NO ACTION
    ON UPDATE NO ACTION)