无法添加或更新子行。外键约束失败

Question

我想做什么

我尝试修改之前设置的NOT NULL字段以接受NULL值。

当我尝试插入记录时，我收到此错误：

A foreign key constraint failed.

我的架构中有两个表，一个名为Customer，另一个名为referralAgent，其中定义了 一对多 关系在它们之间，使用referralAgentId作为customer表的外键。

虽然父表的字段中没有任何NOT NULL约束，即customer，但我无法在外键字段中插入NULL值。

和CREATE TABLE代码：

CREATE TABLE IF NOT EXISTS `watson_schema`.`referralagent` (
  `idReferralAgent` INT(11) NOT NULL,
  `firstName` VARCHAR(45) NOT NULL,
  `lastName` VARCHAR(45) NOT NULL,
  `test` VARCHAR(45) NULL DEFAULT NULL,
  PRIMARY KEY (`idReferralAgent`))
ENGINE = InnoDB
AUTO_INCREMENT = 6
DEFAULT CHARACTER SET = latin1;


CREATE TABLE IF NOT EXISTS `watson_schema`.`customer` (
  `idUser` INT(11) NOT NULL AUTO_INCREMENT,
  `firstName` VARCHAR(45) NOT NULL,
  `lastName` VARCHAR(45) NOT NULL,
  `address` VARCHAR(80) NOT NULL,
  `postCode` VARCHAR(45) NOT NULL,
  `profession` VARCHAR(45) NOT NULL,
  `phoneNumWork` VARCHAR(16) NOT NULL,
  `phoneNumMobile` VARCHAR(16) NOT NULL,
  `phoneNumHome` VARCHAR(16) NOT NULL,
  `nationality` INT(11) NOT NULL,
  `countryResidence` INT(11) NOT NULL,
  `countryBirth` INT(11) NOT NULL,
  `entityStatusIdStatus` INT(11) NOT NULL,
  `ReferralAgent_idReferralAgent` INT(11) NULL DEFAULT NULL,
  PRIMARY KEY (`idUser`),
  INDEX `fk_Customers_nationality1_idx` (`nationality` ASC),
  INDEX `fk_Customers_Country1_idx` (`countryResidence` ASC),
  INDEX `fk_Customers_Country2_idx` (`countryBirth` ASC),
  INDEX `fk_Customer_EntityStatus1_idx` (`entityStatusIdStatus` ASC),
  INDEX `fk_Customer_ReferralAgent1_idx` (`ReferralAgent_idReferralAgent` ASC),
  CONSTRAINT `fk_Customers_Country1`
    FOREIGN KEY (`countryResidence`)
    REFERENCES `watson_schema`.`country` (`idCountry`)
    ON DELETE NO ACTION
    ON UPDATE NO ACTION,
  CONSTRAINT `fk_Customers_Country2`
    FOREIGN KEY (`countryBirth`)
    REFERENCES `watson_schema`.`country` (`idCountry`)
    ON DELETE NO ACTION
    ON UPDATE NO ACTION,
  CONSTRAINT `fk_Customers_nationality1`
    FOREIGN KEY (`nationality`)
    REFERENCES `watson_schema`.`nationality` (`idNationality`)
    ON DELETE NO ACTION
    ON UPDATE NO ACTION,
  CONSTRAINT `fk_Customer_EntityStatus1`
    FOREIGN KEY (`entityStatusIdStatus`)
    REFERENCES `watson_schema`.`entitystatus` (`idStatus`)
    ON DELETE NO ACTION
    ON UPDATE NO ACTION,
  CONSTRAINT `fk_Customer_ReferralAgent1`
    FOREIGN KEY (`ReferralAgent_idReferralAgent`)
    REFERENCES `watson_schema`.`referralagent` (`idReferralAgent`)
    ON DELETE NO ACTION
    ON UPDATE NO ACTION)
ENGINE = InnoDB
AUTO_INCREMENT = 21
DEFAULT CHARACTER SET = utf8;

INSERT INTO `watson_schema`.`customer`
(`idUser`,
`firstName`,
`lastName`,
`address`,
`postCode`,
`profession`,
`phoneNumWork`,
`phoneNumMobile`,
`phoneNumHome`,
`nationality`,
`countryResidence`,
`countryBirth`,
`entityStatusIdStatus`,
`ReferralAgent_idReferralAgent`)
VALUES
("22",
"Giannis",
"Komikos",
"Theofilou",
"2242",
"Coffeeman",
"22345672",
"99874568",
"22454547",
"6",
"2",
"3",
"5",
"");

Answer 1

您没有插入null。您正在插入一个空字符串。将ReferralAgent_idReferralAgent从insert语句中删除或将insert语句中的最后一个值从“”更改为NULL。插入失败，因为父表中没有等于“”的键。