Question

我知道这个问题已经在这个网站上出现了很多次，但是可以看出：

1）表中引用的任何外键都是最初定义它的表中的主键或唯一键。
2）没有两个外键具有相同的名称（dname，dname1等）
3）InnoDB用于所有表格。

任何想法可能导致错误1215？这就是错误所说的：

Executing SQL script in server
ERROR: Error 1215: Cannot add foreign key constraint
SQL Code:
        -- -----------------------------------------------------
        -- Table `mydb`.`major`
        -- -----------------------------------------------------
        CREATE TABLE IF NOT EXISTS `mydb`.`major` (
          `dname2` VARCHAR(40) NOT NULL COMMENT '',
          `sid` INT NOT NULL COMMENT '',
          PRIMARY KEY (`dname2`, `sid`)  COMMENT '',
          INDEX `sid_idx` (`sid` ASC)  COMMENT '',
          CONSTRAINT `dname2`
            FOREIGN KEY (`dname2`)
            REFERENCES `mydb`.`dept` (`dname`)
            ON DELETE CASCADE
            ON UPDATE CASCADE,
          CONSTRAINT `sid`
            FOREIGN KEY (`sid`)
            REFERENCES `mydb`.`student` (`sid`)
            ON DELETE CASCADE
            ON UPDATE CASCADE)
        ENGINE = InnoDB

SQL script execution finished: statements: 9 succeeded, 1 failed

Fetching back view definitions in final form.
Nothing to fetch

这是我的代码开始的地方：

-- 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 mydb
-- -----------------------------------------------------

-- -----------------------------------------------------
-- Schema mydb
-- -----------------------------------------------------
CREATE SCHEMA IF NOT EXISTS `mydb` DEFAULT CHARACTER SET utf8 COLLATE utf8_general_ci ;
USE `mydb` ;

-- -----------------------------------------------------
-- Table `mydb`.`student`
-- -----------------------------------------------------
CREATE TABLE IF NOT EXISTS `mydb`.`student` (
  `sid` INT NOT NULL COMMENT '',
  `sname` VARCHAR(40) NOT NULL COMMENT '',
  `sex` VARCHAR(7) NOT NULL COMMENT '',
  `age` INT NOT NULL COMMENT '',
  `year` INT NOT NULL COMMENT '',
  `gpa` DOUBLE NOT NULL COMMENT '',
  PRIMARY KEY (`sid`)  COMMENT '')
ENGINE = InnoDB;


-- -----------------------------------------------------
-- Table `mydb`.`dept`
-- -----------------------------------------------------
CREATE TABLE IF NOT EXISTS `mydb`.`dept` (
  `dname` VARCHAR(40) NOT NULL COMMENT '',
  `numphds` INT NOT NULL COMMENT '',
  PRIMARY KEY (`dname`)  COMMENT '')
ENGINE = InnoDB;


-- -----------------------------------------------------
-- Table `mydb`.`prof`
-- -----------------------------------------------------
CREATE TABLE IF NOT EXISTS `mydb`.`prof` (
  `pname` VARCHAR(40) NOT NULL COMMENT '',
  `dname` VARCHAR(40) NOT NULL COMMENT '',
  PRIMARY KEY (`pname`)  COMMENT '',
  INDEX `dname_idx` (`dname` ASC)  COMMENT '',
  CONSTRAINT `dname`
    FOREIGN KEY (`dname`)
    REFERENCES `mydb`.`dept` (`dname`)
    ON DELETE CASCADE
    ON UPDATE CASCADE)
ENGINE = InnoDB;


-- -----------------------------------------------------
-- Table `mydb`.`course`
-- -----------------------------------------------------
CREATE TABLE IF NOT EXISTS `mydb`.`course` (
  `cno` VARCHAR(10) NOT NULL COMMENT '',
  `cname` VARCHAR(40) NOT NULL COMMENT '',
  `dname1` VARCHAR(40) NOT NULL COMMENT '',
  PRIMARY KEY (`cno`, `dname1`)  COMMENT '',
  INDEX `dname_idx` (`dname1` ASC)  COMMENT '',
  CONSTRAINT `dname1`
    FOREIGN KEY (`dname1`)
    REFERENCES `mydb`.`dept` (`dname`)
    ON DELETE CASCADE
    ON UPDATE CASCADE)
ENGINE = InnoDB;


-- -----------------------------------------------------
-- Table `mydb`.`major`
-- -----------------------------------------------------
CREATE TABLE IF NOT EXISTS `mydb`.`major` (
  `dname2` VARCHAR(40) NOT NULL COMMENT '',
  `sid` INT NOT NULL COMMENT '',
  PRIMARY KEY (`dname2`, `sid`)  COMMENT '',
  INDEX `sid_idx` (`sid` ASC)  COMMENT '',
  CONSTRAINT `dname2`
    FOREIGN KEY (`dname2`)
    REFERENCES `mydb`.`dept` (`dname`)
    ON DELETE CASCADE
    ON UPDATE CASCADE,
  CONSTRAINT `sid`
    FOREIGN KEY (`sid`)
    REFERENCES `mydb`.`student` (`sid`)
    ON DELETE CASCADE
    ON UPDATE CASCADE)
ENGINE = InnoDB;


-- -----------------------------------------------------
-- Table `mydb`.`section`
-- -----------------------------------------------------
CREATE TABLE IF NOT EXISTS `mydb`.`section` (
  `dname3` VARCHAR(40) NOT NULL COMMENT '',
  `cno` VARCHAR(10) NOT NULL COMMENT '',
  `sectno` INT NOT NULL COMMENT '',
  `pname` VARCHAR(40) NOT NULL COMMENT '',
  PRIMARY KEY (`dname3`, `cno`, `sectno`)  COMMENT '',
  INDEX `cno_idx` (`pname` ASC)  COMMENT '',
  CONSTRAINT `dname3`
    FOREIGN KEY (`cno`)
    REFERENCES `mydb`.`dept` (`dname`)
    ON DELETE CASCADE
    ON UPDATE CASCADE,
  CONSTRAINT `cno`
    FOREIGN KEY (`pname`)
    REFERENCES `mydb`.`course` (`cno`)
    ON DELETE CASCADE
    ON UPDATE CASCADE,
  CONSTRAINT `pname`
    FOREIGN KEY ()
    REFERENCES `mydb`.`prof` ()
    ON DELETE CASCADE
    ON UPDATE CASCADE)
ENGINE = InnoDB;


-- -----------------------------------------------------
-- Table `mydb`.`enroll`
-- -----------------------------------------------------
CREATE TABLE IF NOT EXISTS `mydb`.`enroll` (
  `sid1` INT NOT NULL COMMENT '',
  `grade` INT NOT NULL COMMENT '',
  `dname4` VARCHAR(40) NOT NULL COMMENT '',
  `cno1` VARCHAR(10) NOT NULL COMMENT '',
  `sectno` INT NOT NULL COMMENT '',
  PRIMARY KEY (`sid1`, `dname4`, `cno1`, `sectno`)  COMMENT '',
  INDEX `dname_idx` (`dname4` ASC)  COMMENT '',
  INDEX `cno_idx` (`cno1` ASC)  COMMENT '',
  INDEX `sectno_idx` (`sectno` ASC)  COMMENT '',
  CONSTRAINT `sid1`
    FOREIGN KEY (`sid1`)
    REFERENCES `mydb`.`student` (`sid`)
    ON DELETE CASCADE
    ON UPDATE CASCADE,
  CONSTRAINT `dname4`
    FOREIGN KEY (`dname4`)
    REFERENCES `mydb`.`dept` (`dname`)
    ON DELETE CASCADE
    ON UPDATE CASCADE,
  CONSTRAINT `cno1`
    FOREIGN KEY (`cno1`)
    REFERENCES `mydb`.`course` (`cno`)
    ON DELETE CASCADE
    ON UPDATE CASCADE,
  CONSTRAINT `sectno`
    FOREIGN KEY (`sectno`)
    REFERENCES `mydb`.`section` (`sectno`)
    ON DELETE CASCADE
    ON UPDATE CASCADE)
ENGINE = InnoDB;


SET SQL_MODE=@OLD_SQL_MODE;
SET FOREIGN_KEY_CHECKS=@OLD_FOREIGN_KEY_CHECKS;
SET UNIQUE_CHECKS=@OLD_UNIQUE_CHECKS;

Answer 1

这些定义存在两个问题：

没有为此外键定义提供名称。

CONSTRAINT `pname`
    FOREIGN KEY ()
    REFERENCES `mydb`.`prof` ()
    ON DELETE CASCADE
    ON UPDATE CASCADE

注册表正在尝试在主键索引中的非前导列上创建外键。

CONSTRAINT `sectno`
    FOREIGN KEY (`sectno`)
    REFERENCES `mydb`.`section` (`sectno`)
    ON DELETE CASCADE
    ON UPDATE CASCADE

部分定义的索引是

PRIMARY KEY (`dname3`, `cno`, `sectno`)  COMMENT '',

使用此索引结构，无法强制执行外键。将sectno移动到索引中的第一个键将支持外键。

试图转发工程师时出错？ SQL错误1215

1 个答案: