Question

我正在尝试为学校项目创建报纸系统，这是该代码的一部分。出于某种原因，我得到“错误代码：1215。无法添加外键约束”

-- MySQL Workbench Forward Engineering

SET @OLD_UNIQUE_CHECKS=@@UNIQUE_CHECKS, UNIQUE_CHECKS=0;
SET @OLD_FOREIGN_KEY_CHECKS=@@FOREIGN_KEY_CHECKS, FOREIGN_KEY_CHECKS=0;
SET @OLD_SQL_MODE=@@SQL_MODE, SQL_MODE='TRADITIONAL,ALLOW_INVALID_DATES';

-- -----------------------------------------------------
-- Schema nyheterhiof
-- -----------------------------------------------------

-- -----------------------------------------------------
-- Schema nyheterhiof
-- -----------------------------------------------------
CREATE SCHEMA IF NOT EXISTS nyheterhiof DEFAULT CHARACTER SET utf8 ;
USE nyheterhiof ;

-- -----------------------------------------------------
-- Table nyheterhiof.newspapers
-- -----------------------------------------------------
CREATE TABLE IF NOT EXISTS nyheterhiof.newspapers (
  newspaper_id INT(11) NOT NULL,
  newspaper_name VARCHAR(45) NULL,
  newspaper_city VARCHAR(45) NULL,
  PRIMARY KEY (newspaper_id),
  UNIQUE INDEX newspaper_id_UNIQUE (newspaper_id ASC))
ENGINE = InnoDB;


-- -----------------------------------------------------
-- Table nyheterhiof.newspaper_Issues
-- -----------------------------------------------------
CREATE TABLE IF NOT EXISTS nyheterhiof.newspaper_issues (
  newspaper_issiue_id INT(11) NOT NULL,
  newspaper_id VARCHAR(45) NOT NULL,
  publication_date DATE NOT NULL,
  comment VARCHAR(200) NULL,
  PRIMARY KEY (newspaper_issiue_id),
  UNIQUE INDEX newspaper_issiue_id_UNIQUE (newspaper_issiue_id ASC),
  INDEX fk_newspaper_Issues_newspapers1_idx (newspaper_id ASC),
  CONSTRAINT fk_newspaper_Issues_newspapers1
    FOREIGN KEY (newspaper_id)
    REFERENCES newspapers (newspaper_id)
    ON DELETE NO ACTION
    ON UPDATE NO ACTION)
ENGINE = InnoDB;

我尝试将FK移动到alter table语句，我尝试在“newspaper_issiues”中为newspaper_id添加索引。

Answer 1

您已指定

CREATE TABLE IF NOT EXISTS nyheterhiof.newspapers (
  newspaper_id INT(11) NOT NULL,

和

CREATE TABLE IF NOT EXISTS nyheterhiof.newspaper_issues (
  ...
  newspaper_id VARCHAR(45) NOT NULL,

这就是问题所在。外键约束 MUST 两端的列在类型和宽度上匹配。

将newspaper_issues.newspaper_id重新定义为 INT ，您将会很高兴。

外键没有“工作”？

1 个答案: