Can't delete row in MySQL error 1451. Need to implement DELETE ON CASCADE

Question

I want to delete a record based on an id. But I can't since foreign key constraint fails...that means that maybe I need to implement DELETE on Cascade...but I don't know how that works. Bottom Line I need to fix the error, and/or I need to implement Delete on Cascade since I searched through the site and that is the most possible solution. This is the query:

SET SQL_SAFE_UPDATES = 0;
DELETE `rentals`, `rental_movie`
FROM `rentals`
LEFT JOIN `rental_movie`
    ON `rentals`.`idRentals` = `rental_movie`.`Rentals_idRentals`
WHERE `Movie_idMovie` = 1;

I have the Error 1451 in MySQL:

Error Code: 1451. Cannot delete or update a parent row: a foreign key constraint fails (`project`.`rental_movie`, CONSTRAINT `fk_Rental_Movie_Rentals1` FOREIGN KEY (`Rentals_idRentals`) REFERENCES `rentals` (`idRentals`) ON DELETE NO ACTION ON UPDATE NO ACTION)

This is my database:

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';

CREATE SCHEMA IF NOT EXISTS `project` DEFAULT CHARACTER SET utf8 ;
USE `project` ;

-- -----------------------------------------------------
-- Table `project`.`customer`
-- -----------------------------------------------------
DROP TABLE IF EXISTS `project`.`customer` ;

CREATE TABLE IF NOT EXISTS `project`.`customer` (
  `idCustomer` INT(11) NOT NULL AUTO_INCREMENT,
  `CustomerName` VARCHAR(20) NOT NULL,
  `CustomerLastName` VARCHAR(20) NOT NULL,
  `CustomerAddressl` VARCHAR(45) NOT NULL,
  `ZipCode` INT(11) NOT NULL,
  `CustomerPueblo` VARCHAR(20) NOT NULL,
  `CustomerTel` DECIMAL(10,0) NOT NULL,
  PRIMARY KEY (`idCustomer`))
ENGINE = InnoDB
AUTO_INCREMENT = 2
DEFAULT CHARACTER SET = utf8;


-- -----------------------------------------------------
-- Table `project`.`movie`
-- -----------------------------------------------------
DROP TABLE IF EXISTS `project`.`movie` ;

CREATE TABLE IF NOT EXISTS `project`.`movie` (
  `idMovie` INT(11) NOT NULL AUTO_INCREMENT,
  `TitleMovie` VARCHAR(45) NOT NULL,
  `Genre` VARCHAR(45) NOT NULL,
  `ReleaseDate` VARCHAR(45) NOT NULL,
  `RunTime` TIME NOT NULL,
  `Rated` VARCHAR(10) NOT NULL,
  PRIMARY KEY (`idMovie`))
ENGINE = InnoDB
AUTO_INCREMENT = 2
DEFAULT CHARACTER SET = utf8;


-- -----------------------------------------------------
-- Table `project`.`rentals`
-- -----------------------------------------------------
DROP TABLE IF EXISTS `project`.`rentals` ;

CREATE TABLE IF NOT EXISTS `project`.`rentals` (
  `idRentals` INT(11) NOT NULL AUTO_INCREMENT,
  `Customer_idCustomer` INT(11) NOT NULL,
  `RentedDate` DATE NOT NULL,
  `ReturnDate` DATE NULL DEFAULT NULL,
  PRIMARY KEY (`idRentals`),
  INDEX `fk_Rentals_Customer_idx` (`Customer_idCustomer` ASC),
  CONSTRAINT `fk_Rentals_Customer`
    FOREIGN KEY (`Customer_idCustomer`)
    REFERENCES `project`.`customer` (`idCustomer`)
    ON DELETE NO ACTION
    ON UPDATE NO ACTION)
ENGINE = InnoDB
AUTO_INCREMENT = 2
DEFAULT CHARACTER SET = utf8;


-- -----------------------------------------------------
-- Table `project`.`rental_movie`
-- -----------------------------------------------------
DROP TABLE IF EXISTS `project`.`rental_movie` ;

CREATE TABLE IF NOT EXISTS `project`.`rental_movie` (
  `Movie_idMovie` INT(11) NOT NULL,
  `Rentals_idRentals` INT(11) NOT NULL,
  PRIMARY KEY (`Movie_idMovie`, `Rentals_idRentals`),
  INDEX `fk_Rental_Movie_Rentals1_idx` (`Rentals_idRentals` ASC),
  CONSTRAINT `fk_Rental_Movie_Movie1`
    FOREIGN KEY (`Movie_idMovie`)
    REFERENCES `project`.`movie` (`idMovie`)
    ON DELETE NO ACTION
    ON UPDATE NO ACTION,
  CONSTRAINT `fk_Rental_Movie_Rentals1`
    FOREIGN KEY (`Rentals_idRentals`)
    REFERENCES `project`.`rentals` (`idRentals`)
    ON DELETE NO ACTION
    ON UPDATE NO ACTION)
ENGINE = InnoDB
DEFAULT CHARACTER SET = utf8;


-- -----------------------------------------------------
-- Table `project`.`transaction`
-- -----------------------------------------------------
DROP TABLE IF EXISTS `project`.`transaction` ;

CREATE TABLE IF NOT EXISTS `project`.`transaction` (
  `idTransaction` INT(11) NOT NULL AUTO_INCREMENT,
  `idRentals` INT(11) NOT NULL,
  `DaysRented` INT(11) NULL DEFAULT NULL,
  `Cost` DECIMAL(10,0) NULL DEFAULT NULL,
  `TotalCost` DECIMAL(10,0) NULL DEFAULT NULL,
  PRIMARY KEY (`idTransaction`),
  INDEX `idRentals_idx` (`idRentals` ASC),
  CONSTRAINT `idRentals`
    FOREIGN KEY (`idRentals`)
    REFERENCES `project`.`rentals` (`idRentals`)
    ON DELETE NO ACTION
    ON UPDATE NO ACTION)
ENGINE = InnoDB
AUTO_INCREMENT = 2
DEFAULT CHARACTER SET = utf8;

USE `project` ;

-- -----------------------------------------------------
-- Placeholder table for view `project`.`new_view`
-- -----------------------------------------------------
CREATE TABLE IF NOT EXISTS `project`.`new_view` (`idRentals` INT, `Customer_idCustomer` INT);

-- -----------------------------------------------------
-- Placeholder table for view `project`.`rentals_view`
-- -----------------------------------------------------
CREATE TABLE IF NOT EXISTS `project`.`rentals_view` (`idRentals` INT, `idCustomer` INT, `CustomerName` INT, `idMovie` INT, `TitleMovie` INT, `RentedDate` INT);

-- -----------------------------------------------------
-- procedure PName
-- -----------------------------------------------------

USE `project`;
DROP procedure IF EXISTS `project`.`PName`;

DELIMITER $$
USE `project`$$
CREATE DEFINER=`root`@`localhost` PROCEDURE `PName`(cid INT)
BEGIN

  SELECT * FROM rentals;

END$$

DELIMITER ;

-- -----------------------------------------------------
-- View `project`.`new_view`
-- -----------------------------------------------------
DROP VIEW IF EXISTS `project`.`new_view` ;
DROP TABLE IF EXISTS `project`.`new_view`;
USE `project`;
CREATE  OR REPLACE ALGORITHM=UNDEFINED DEFINER=`root`@`localhost` SQL SECURITY DEFINER VIEW `project`.`new_view` AS select `project`.`rentals`.`idRentals` AS `idRentals`,`project`.`rentals`.`Customer_idCustomer` AS `Customer_idCustomer` from `project`.`rentals`;

-- -----------------------------------------------------
-- View `project`.`rentals_view`
-- -----------------------------------------------------
DROP VIEW IF EXISTS `project`.`rentals_view` ;
DROP TABLE IF EXISTS `project`.`rentals_view`;
USE `project`;
CREATE  OR REPLACE ALGORITHM=UNDEFINED DEFINER=`root`@`localhost` SQL SECURITY DEFINER VIEW `project`.`rentals_view` AS select `r`.`idRentals` AS `idRentals`,`c`.`idCustomer` AS `idCustomer`,`c`.`CustomerName` AS `CustomerName`,`m`.`idMovie` AS `idMovie`,`m`.`TitleMovie` AS `TitleMovie`,`r`.`RentedDate` AS `RentedDate` from (((`project`.`rentals` `r` join `project`.`customer` `c` on((`r`.`Customer_idCustomer` = `c`.`idCustomer`))) join `project`.`rental_movie` `rm` on((`rm`.`Rentals_idRentals` = `r`.`idRentals`))) join `project`.`movie` `m` on((`rm`.`Movie_idMovie` = `m`.`idMovie`)));

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

Answer 1

You need a foreign key declared with the ON DELETE CASCADE option.

-- -----------------------------------------------------
-- Table `project`.`rental_movie`
-- -----------------------------------------------------
DROP TABLE IF EXISTS `project`.`rental_movie` ;

CREATE TABLE IF NOT EXISTS `project`.`rental_movie` (
  `Movie_idMovie` INT(11) NOT NULL,
  `Rentals_idRentals` INT(11) NOT NULL,
  PRIMARY KEY (`Movie_idMovie`, `Rentals_idRentals`),
  INDEX `fk_Rental_Movie_Rentals1_idx` (`Rentals_idRentals` ASC),
  CONSTRAINT `fk_Rental_Movie_Movie1`
    FOREIGN KEY (`Movie_idMovie`)
    REFERENCES `project`.`movie` (`idMovie`)
    ON DELETE NO ACTION
    ON UPDATE NO ACTION,
  CONSTRAINT `fk_Rental_Movie_Rentals1`
    FOREIGN KEY (`Rentals_idRentals`)
    REFERENCES `project`.`rentals` (`idRentals`)
    ON DELETE CASCADE
    ON UPDATE CASCADE)
ENGINE = InnoDB
DEFAULT CHARACTER SET = utf8;

Then if you remove the value in rental_movie.Rentals_idRentals, it will automatically remove the value in rentals.idRentals.

This remove will be simultaneous and atomic -- that is, no other query running concurrently will be able to see the data removed in one table and not removed in the other table.

Answer 2

Perhaps you should consider dropping the rental_movie table, and move the Movie_idMovie column onto the rentals table, since it's a 1-to-1 relationship, this table you've created will cause you grief like you've already experienced.

DROP TABLE `project`.`rental_movie`;

ALTER TABLE `project`.`rentals` 
ADD COLUMN `Movie_idMovie` INT(11) NOT NULL AFTER `Customer_idCustomer`,
ADD INDEX `fk_Rentals_Movie_idx` (`Movie_idMovie` ASC);
ALTER TABLE `project`.`rentals` 
ADD CONSTRAINT `fk_Rentals_Movie`
        FOREIGN KEY (`Movie_idMovie`)
        REFERENCES `project`.`movie` (`idMovie`)
        ON DELETE NO ACTION
        ON UPDATE NO ACTION;