一个带有2个参考表的外键 [英] One Foreign Key with 2 References Table

问题描述

是否可以使用带有两个参考表的外键?

is it possible to have a foreign key with two reference tables?

这是脚本，我们在插入该表时遇到了问题

here's the script and we're having a problem inserting into this table

CREATE TABLE Class(
    idNumber varchar(30) not null,
    day varchar(10) not null,
    time varchar(20) not null,
    foreign key(idNumber) REFERENCES ThesisMember(idNumber),
    foreign key(idNumber) REFERENCES Faculty(idNumber),
    PRIMARY KEY(idNumber,day,time)
);

CONSTRAINT `class_ibfk_1`
    FOREIGN KEY (`idNumber`) REFERENCES `thesismember` (`idNumber`)) 

SQL语句:

INSERT INTO `thesis`.`class`
    (`idNumber`, `day`, `time`) VALUES ('9990', 'F', '0940-1110')

学院"表的idNumber为"9990".

the Faculty table has the "9990" idNumber.

推荐答案

FK约束要求字段'idNumber'的每个实例都出现在所有引用的表中.您声明只有一个被引用的表具有要插入的值，因此在INSERT尝试中当然会发生错误.

The FK constraint requires that every instance of the field 'idNumber' occur in ALL referenced tables. You state that only one of the referenced tables has the value to be inserted, so of course an error occurs on the INSERT attempt.

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