Question

这里我正在为我的SQL做外键关系，我有3个表

产品
库
报价

这里product表是一个主表，gallery，offer表是子表，现在我试图删除主表项，但它没有发生我收到的错误就像

无法删除或更新父行：外键约束失败

    CREATE TABLE `product` (
 `productId` int(11) NOT NULL AUTO_INCREMENT,
 `name` varchar(100) COLLATE utf16_bin NOT NULL,
 `price` decimal(10,0) NOT NULL,
 `regOn` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
 PRIMARY KEY (`productId`)
) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=utf16 COLLATE=utf16_bin

CREATE TABLE `offer` (
 `offerId` int(11) NOT NULL AUTO_INCREMENT,
 `productId` int(11) NOT NULL,
 `offerpercentage` text COLLATE utf16_bin NOT NULL,
 PRIMARY KEY (`offerId`),
 KEY `productId` (`productId`),
 CONSTRAINT `offer_ibfk_1` FOREIGN KEY (`productId`) REFERENCES `product` (`productId`)
) ENGINE=InnoDB AUTO_INCREMENT=2 DEFAULT CHARSET=utf16 COLLATE=utf16_bin

CREATE TABLE `gallery` (
 `galleryId` int(11) NOT NULL AUTO_INCREMENT,
 `productId` int(11) NOT NULL,
 `galleryName` text COLLATE utf16_bin NOT NULL,
 PRIMARY KEY (`galleryId`),
 KEY `productId` (`productId`),
 CONSTRAINT `gallery_ibfk_1` FOREIGN KEY (`productId`) REFERENCES `product` (`productId`)
) ENGINE=InnoDB AUTO_INCREMENT=4 DEFAULT CHARSET=utf16 COLLATE=utf16_bin

预期输出

Suppose I am deleting master table entry means i have to delete all child tables entry also

Answer 1

您需要将ON DELETE CASCADE应用于外键引用。

CREATE TABLE `product` (
 `productId` int(11) NOT NULL AUTO_INCREMENT,
 `name` varchar(100) COLLATE utf16_bin NOT NULL,
 `price` decimal(10,0) NOT NULL,
 `regOn` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
 PRIMARY KEY (`productId`)
) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=utf16 COLLATE=utf16_bin

CREATE TABLE `offer` (
 `offerId` int(11) NOT NULL AUTO_INCREMENT,
 `productId` int(11) NOT NULL,
 `offerpercentage` text COLLATE utf16_bin NOT NULL,
 PRIMARY KEY (`offerId`),
 KEY `productId` (`productId`),
 CONSTRAINT `offer_ibfk_1` FOREIGN KEY (`productId`) REFERENCES `product` (`productId`) ON DELETE CASCADE
) ENGINE=InnoDB AUTO_INCREMENT=2 DEFAULT CHARSET=utf16 COLLATE=utf16_bin

CREATE TABLE `gallery` (
 `galleryId` int(11) NOT NULL AUTO_INCREMENT,
 `productId` int(11) NOT NULL,
 `galleryName` text COLLATE utf16_bin NOT NULL,
 PRIMARY KEY (`galleryId`),
 KEY `productId` (`productId`),
 CONSTRAINT `gallery_ibfk_1` FOREIGN KEY (`productId`) REFERENCES `product` (`productId`) ON DELETE CASCADE
) ENGINE=InnoDB AUTO_INCREMENT=4 DEFAULT CHARSET=utf16 COLLATE=utf16_bin

这告诉MySQL当父项被删除时，删除引用子项。

外键关系在mysql中不起作用

1 个答案: