I have created tables in MYSQL as follows
Author Table
CREATE TABLE `author` (
`AuthorId` varchar(25) NOT NULL,
`AuthorName` varchar(50) NOT NULL,
PRIMARY KEY (`AuthorId`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1
Books Table
CREATE TABLE `books` (
`DocId` int(11) NOT NULL,
`ISBN` varchar(13) NOT NULL,
PRIMARY KEY (`DocId`),
KEY `DocId` (`DocId`),
CONSTRAINT `books_ibfk_1` FOREIGN KEY (`DocId`) REFERENCES `document`
(`DocId`)
ON DELETE CASCADE ON UPDATE CASCADE
) ENGINE=InnoDB DEFAULT CHARSET=latin1
Document Table
CREATE TABLE `document` (
`DocId` int(11) NOT NULL,
`Title` varchar(50) NOT NULL,
`PublishDate` date DEFAULT NULL,
`AuthorId` varchar(10) DEFAULT NULL,
`DocType` varchar(10) DEFAULT NULL,
PRIMARY KEY (`DocId`),
KEY `AuthorId` (`AuthorId`),
CONSTRAINT `document_ibfk_3` FOREIGN KEY (`AuthorId`) REFERENCES `author`
(`AuthorId`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1
I made a server for my PHP website on XAMPP and am using mysql but when I try inserting the values in Document table I get
error while inserting the recordsCannot add or update a child row: a foreign
key constraint fails (`librarydb`.`document`, CONSTRAINT `document_ibfk_3`
FOREIGN KEY (`AuthorId`) REFERENCES `author` (`AuthorId`))
How do I resolve this issue?
Your linked fields author.AuthorId
and document.AuthorId
are not defined the same way.
From the docs:
Corresponding columns in the foreign key and the referenced key must have similar data types. The size and sign of integer types must be the same. The length of string types need not be the same.
So make them both varchar(10) NOT NULL - or whatever you need.