错误 1452:无法添加或更新子行:外键约束失败

问题描述

我在 MySQL Workbench 中创建了表，如下所示:

I have created tables in MySQL Workbench as shown below :

ORDRE 表:

CREATE TABLE Ordre (
  OrdreID   INT NOT NULL,
  OrdreDato DATE DEFAULT NULL,
  KundeID   INT  DEFAULT NULL,
  CONSTRAINT Ordre_pk PRIMARY KEY (OrdreID),
  CONSTRAINT Ordre_fk FOREIGN KEY (KundeID) REFERENCES Kunde (KundeID)
)
  ENGINE = InnoDB;

PRODUKT 表:

CREATE TABLE Produkt (
  ProduktID          INT NOT NULL,
  ProduktBeskrivelse VARCHAR(100) DEFAULT NULL,
  ProduktFarge       VARCHAR(20)  DEFAULT NULL,
  Enhetpris          INT          DEFAULT NULL,
  CONSTRAINT Produkt_pk PRIMARY KEY (ProduktID)
)
  ENGINE = InnoDB;

和ORDRELINJE表:

CREATE TABLE Ordrelinje (
  Ordre         INT NOT NULL,
  Produkt       INT NOT NULL,
  AntallBestilt INT DEFAULT NULL,
  CONSTRAINT Ordrelinje_pk PRIMARY KEY (Ordre, Produkt),
  CONSTRAINT Ordrelinje_fk FOREIGN KEY (Ordre) REFERENCES Ordre (OrdreID),
  CONSTRAINT Ordrelinje_fk1 FOREIGN KEY (Produkt) REFERENCES Produkt (ProduktID)
)
  ENGINE = InnoDB;

所以当我尝试将值插入 ORDRELINJE 表时，我得到:

so when I try to insert values into ORDRELINJE table i get:

错误代码:1452.无法添加或更新子行:外键约束失败(srdjank.Ordrelinje, CONSTRAINT Ordrelinje_fk FOREIGNKEY (Ordre) REFERENCES Ordre (OrdreID))

Error Code: 1452. Cannot add or update a child row: a foreign key constraint fails (srdjank.Ordrelinje, CONSTRAINT Ordrelinje_fk FOREIGN KEY (Ordre) REFERENCES Ordre (OrdreID))

我看过关于这个主题的其他帖子，但没有运气.我是否在监督某事或知道该怎么做?

I've seen the other posts on this topic, but no luck. Am I overseeing something or any idea what to do?

推荐答案

摘自 使用外键约束

外键关系涉及一个父表，其中包含中心数据值，以及具有相同值指向的子表回到它的父母.FOREIGN KEY 子句在子句中指定表.

Foreign key relationships involve a parent table that holds the central data values, and a child table with identical values pointing back to its parent. The FOREIGN KEY clause is specified in the child table.

它将拒绝任何试图创建的 INSERT 或 UPDATE 操作如果没有匹配项，则为子表中的外键值父表中的候选键值.

It will reject any INSERT or UPDATE operation that attempts to create a foreign key value in a child table if there is no a matching candidate key value in the parent table.

所以你的错误 Error Code: 1452. Cannot add or update a child row: a foreign key constraint failed 本质上意味着，你正试图向你的 Ordrelinje 添加一行Ordre 表中不存在匹配行 (OrderID) 的 code> 表.

So your error Error Code: 1452. Cannot add or update a child row: a foreign key constraint fails essentially means that, you are trying to add a row to your Ordrelinje table for which no matching row (OrderID) is present in Ordre table.

您必须先将该行插入到您的 Ordre 表中.

You must first insert the row to your Ordre table.

这篇关于错误 1452:无法添加或更新子行:外键约束失败的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持html5模板网！