MySQL Foreign Key error 1452

Question

When I go to try to add records to my client and/or the site table I get the following error.

Schema Creation Failed: Cannot add or update a child row: a foreign key constraint fails (db_2_6ceaf.client, CONSTRAINT client2offer FOREIGN KEY (clientID) REFERENCES offer_to_client (clientID) ON DELETE NO ACTION ON UPDATE NO ACTION):

Schema:

SQL:

    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';


-- -----------------------------------------------------
-- Table `offer_to_category`
-- -----------------------------------------------------
CREATE  TABLE IF NOT EXISTS `offer_to_category` (
  `offerID` INT UNSIGNED NOT NULL ,
  `categoryID` INT UNSIGNED NOT NULL ,
  INDEX `offer_to_category` (`offerID` ASC, `categoryID` ASC) ,
  INDEX `o2c_categoryID` (`categoryID` ASC) )
ENGINE = InnoDB;


-- -----------------------------------------------------
-- Table `offer_to_client`
-- -----------------------------------------------------
CREATE  TABLE IF NOT EXISTS `offer_to_client` (
  `offerID` INT UNSIGNED NOT NULL ,
  `clientID` INT UNSIGNED NOT NULL ,
  INDEX `offer_to_client` (`offerID` ASC, `clientID` ASC) ,
  INDEX `o2cl_clientID` (`clientID` ASC) )
ENGINE = InnoDB;


-- -----------------------------------------------------
-- Table `offer`
-- -----------------------------------------------------
CREATE  TABLE IF NOT EXISTS `offer` (
  `offerID` INT UNSIGNED NOT NULL AUTO_INCREMENT ,
  `offerName` VARCHAR(255) NULL ,
  `offerDescription` LONGTEXT NULL ,
  `offerAction` TEXT NULL ,
  `offerStart` BIGINT NULL ,
  `offerEnd` BIGINT NULL ,
  `offerStatus` TINYINT(1) NULL ,
  PRIMARY KEY (`offerID`) ,
  CONSTRAINT `offer2cat`
    FOREIGN KEY (`offerID` )
    REFERENCES `offer_to_category` (`offerID` )
    ON DELETE CASCADE
    ON UPDATE NO ACTION,
  CONSTRAINT `offer2client`
    FOREIGN KEY (`offerID` )
    REFERENCES `offer_to_client` (`offerID` )
    ON DELETE NO ACTION
    ON UPDATE NO ACTION)
ENGINE = InnoDB;


-- -----------------------------------------------------
-- Table `category`
-- -----------------------------------------------------
CREATE  TABLE IF NOT EXISTS `category` (
  `categoryID` INT UNSIGNED NOT NULL AUTO_INCREMENT ,
  `categoryName` VARCHAR(255) NULL ,
  `categoryDescription` LONGTEXT NULL ,
  `categoryStatus` TINYINT(1) NULL ,
  PRIMARY KEY (`categoryID`) ,
  CONSTRAINT `cat2offer`
    FOREIGN KEY (`categoryID` )
    REFERENCES `offer_to_category` (`categoryID` )
    ON DELETE CASCADE
    ON UPDATE NO ACTION)
ENGINE = InnoDB;


-- -----------------------------------------------------
-- Table `user`
-- -----------------------------------------------------
CREATE  TABLE IF NOT EXISTS `user` (
  `userID` INT UNSIGNED NOT NULL AUTO_INCREMENT ,
  `clientID` INT UNSIGNED NOT NULL ,
  `userEmail` VARCHAR(255) NULL ,
  `userFirstName` VARCHAR(255) NULL ,
  `userLastName` VARCHAR(255) NULL ,
  `userRegistered` BIGINT NULL ,
  `userStatus` TINYINT(1) NULL ,
  PRIMARY KEY (`userID`) ,
  INDEX `client` (`clientID` ASC, `userEmail` ASC) )
ENGINE = InnoDB;


-- -----------------------------------------------------
-- Table `client`
-- -----------------------------------------------------
CREATE  TABLE IF NOT EXISTS `client` (
  `clientID` INT UNSIGNED NOT NULL AUTO_INCREMENT ,
  `siteID` INT UNSIGNED NOT NULL ,
  `clientName` VARCHAR(255) NULL ,
  `clientDescription` LONGTEXT NULL ,
  `clientUrl` LONGTEXT NULL ,
  `clientStatus` TINYINT(1) NULL ,
  PRIMARY KEY (`clientID`) ,
  INDEX `clientsiteid` (`siteID` ASC) ,
  CONSTRAINT `client2offer`
    FOREIGN KEY (`clientID` )
    REFERENCES `offer_to_client` (`clientID` )
    ON DELETE NO ACTION
    ON UPDATE NO ACTION,
  CONSTRAINT `client2user`
    FOREIGN KEY (`clientID` )
    REFERENCES `user` (`clientID` )
    ON DELETE CASCADE
    ON UPDATE NO ACTION)
ENGINE = InnoDB;


-- -----------------------------------------------------
-- Table `admins`
-- -----------------------------------------------------
CREATE  TABLE IF NOT EXISTS `admins` (
  `adminID` INT UNSIGNED NOT NULL AUTO_INCREMENT ,
  `adminName` VARCHAR(255) NULL ,
  `adminEmail` LONGTEXT NULL ,
  `adminUsername` VARCHAR(255) NULL ,
  `adminStatus` TINYINT(1) NULL ,
  PRIMARY KEY (`adminID`) )
ENGINE = InnoDB;


-- -----------------------------------------------------
-- Table `site`
-- -----------------------------------------------------
CREATE  TABLE IF NOT EXISTS `site` (
  `siteID` INT UNSIGNED NOT NULL AUTO_INCREMENT ,
  `siteName` VARCHAR(255) NULL ,
  `siteURL` LONGTEXT NULL ,
  `siteStyles` LONGTEXT NULL ,
  `siteImages` LONGTEXT NULL ,
  `sitesStatus` TINYINT(1) NULL ,
  PRIMARY KEY (`siteID`) ,
  CONSTRAINT `site2client`
    FOREIGN KEY (`siteID` )
    REFERENCES `client` (`siteID` )
    ON DELETE NO ACTION
    ON UPDATE NO ACTION)
ENGINE = InnoDB;




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

-- -----------------------------------------------------
-- Data for table `client`
-- -----------------------------------------------------
START TRANSACTION;

INSERT INTO `client` (`clientID`, `siteID`, `clientName`, `clientDescription`, `clientUrl`, `clientStatus`) VALUES (NULL, 1, 'Weight Watchers', 'Weight Watchers microsite', 'weightwachers', 1);
INSERT INTO `client` (`clientID`, `siteID`, `clientName`, `clientDescription`, `clientUrl`, `clientStatus`) VALUES (NULL, 1, 'A Uni', NULL, NULL, 1);
INSERT INTO `client` (`clientID`, `siteID`, `clientName`, `clientDescription`, `clientUrl`, `clientStatus`) VALUES (NULL, 2, 'Ollie Biz', '', NULL, 1);
INSERT INTO `client` (`clientID`, `siteID`, `clientName`, `clientDescription`, `clientUrl`, `clientStatus`) VALUES (NULL, 2, 'Ollie Uni', NULL, 'ollieuni', 1);

COMMIT;

-- -----------------------------------------------------
-- Data for table `site`
-- -----------------------------------------------------
START TRANSACTION;

INSERT INTO `site` (`siteID`, `siteName`, `siteURL`, `siteStyles`, `siteImages`, `sitesStatus`) VALUES (1, 'We Love Rewards', 'http://www.weloverewards.co.uk', NULL, NULL, 1);
INSERT INTO `site` (`siteID`, `siteName`, `siteURL`, `siteStyles`, `siteImages`, `sitesStatus`) VALUES (2, 'Ollie Rewards', 'http://www.olliesrewards.co.uk', NULL, NULL, 1);

COMMIT;

Answer 1

I believe this constraint:

CONSTRAINT `client2offer`
 FOREIGN KEY (`clientID` )
 REFERENCES `offer_to_client` (`clientID` )
 ON DELETE NO ACTION
 ON UPDATE NO ACTION,

Should be moved to be a constraint on the client_to_offer table, not on the client table. At the moment any insert in client must have a matching record in client_to_offer, which I believe is the wrong way around.