SQL

Question

我正在尝试将 accounts table 中的 accountID 字段连接到 customers table 中的外键。到目前为止，这是我的代码：

CREATE TABLE IF NOT EXISTS `items` ( 
`id` int(6) unsigned NOT NULL,
`name` varchar(200) NOT NULL,
PRIMARY KEY (`id`) ) DEFAULT CHARSET=utf8; 

CREATE TABLE IF NOT EXISTS `accounts` ( 
`accountID` int(6) unsigned NOT NULL AUTO_INCREMENT,
`email` varchar(200) NOT NULL,
`passwordHash` varchar(200) NOT NULL,
PRIMARY KEY (`accountID`) ) DEFAULT CHARSET=utf8; 

CREATE TABLE IF NOT EXISTS `customers` ( 
`customerID` int(6) unsigned NOT NULL,
`firstName` varchar(200) NOT NULL,
`lastName` varchar(200) NOT NULL,
`address` varchar(200) NOT NULL,
`accountID` int(6) unsigned NOT NULL,
 PRIMARY KEY (`customerID`),
 CONSTRAINT `FK_accounts_accountID` FOREIGN KEY (`accountID`)
REFERENCES `accounts` (`accountID`) );

CREATE TABLE IF NOT EXISTS `orders` ( 
`id` int(6) unsigned NOT NULL,
`date` DATE NOT NULL,
`customerID` int(6) unsigned NOT NULL,
`paymentAmmount` float(6) unsigned NOT NULL,
 PRIMARY KEY (`id`),
 CONSTRAINT `FK_customers_customerID` FOREIGN KEY (`customerID`)
 REFERENCES `customers` (`customerID`) );

CREATE TABLE IF NOT EXISTS `items-orders` ( 
`id` int(6) unsigned NOT NULL,
`itemId` int(6) unsigned NOT NULL,
`orderId` int(6) unsigned NOT NULL,
`itemQuantity` int(1) unsigned NOT NULL,
PRIMARY KEY (`id`), 
KEY `FK_items_itemId` (`itemId`),
CONSTRAINT `FK_items_itemId` FOREIGN KEY (`itemId`) REFERENCES `items` 
(`id`) ) DEFAULT CHARSET=utf8; 


INSERT INTO `items` (`id`, `name`) VALUES 
('1', 'super cool huge bell'), 
('2', 'iron 20p D&D cube'),
('3', 'Dumbledore wand'),
('4', 'super cool small bell'); 

INSERT INTO `accounts` (`accountID`, `email`, `passwordHash`) VALUES
('1', 'emailAddress', 'lfadaw'),
('2', 'anotherAddress', 'dafaegdwa'),
('3', 'anotherOne', 'gaeeaw');

INSERT INTO `customers`
(`customerID`, `firstName`, `lastName`, `address`) VALUES 
('1', 'moshe', 'rubin', 'haifa'),
('2', 'tanya', 'shelomayev', 'netanya'),
('3', 'itamar', 'ofer', 'haifa'); 

INSERT INTO `orders` (`id`, `date`, `customerID`, `paymentAmmount`) VALUES 
('1', '2019-02-01', '1', '40'), 
('2', '2019-02-01', '3', '361'),
('3', '2018-10-14', '2', '10'); 

INSERT INTO `items-orders` (`id`,`itemId`,`orderId`,`itemQuantity`) VALUES 
('1', '1', '3', '2'),
('2', '4', '3', '10'),
('3', '3', '1', '1'), 
('4', '2', '2', '1');

我将 AUTO_INCREMENT 添加到 accountID 字段，但我仍然收到此错误消息： Field 'accountID' doesn't have a default value.

当我在 tables orders 和 customers 之间链接 customerID 字段时，我没有收到错误。

我确定这是一个以前回答过的问题，但我发现的只是将 AUTO_INCREMENT 添加到该字段的提示，这对我不起作用。任何帮助将不胜感激^^

Answer 1

这是因为您的 customer table 包含一个 accountID 列但约束 NOT NULL 并且没有默认值。

因此，实际上是这个语句导致了问题：

INSERT INTO `customers`
(`customerID`, `firstName`, `lastName`, `address`) VALUES 
('1', 'moshe', 'rubin', 'haifa'),
('2', 'tanya', 'shelomayev', 'netanya'),
('3', 'itamar', 'ofer', 'haifa');

SQL - ID 字段在添加 AUTO_INCREMENT 后仍缺少默认值（SQL Fiddle）

SQL - ID field missing default value even after adding AUTO_INCREMENT (SQL Fiddle)

mysql

default-value

auto-increment