mysql - SQL Fiddle - 无法添加外键约束
问题描述
我在为我的 salesorderslineitem 表构建架构时遇到问题。即使我尝试在小提琴中自行构建模式。我收到一条错误消息,无法添加外键约束...在这里,我的表一起试图让新的 salesorderslineitem 表正常工作。感谢大家!
CREATE TABLE salesorders
( donut_order_id INT(10) NOT NULL AUTO_INCREMENT,
customer_id INT,
date DATETIME,
special_handling_note TEXT,
PRIMARY KEY (donut_order_id),
FOREIGN KEY (customer_id) REFERENCES customers(customer_id)
);
INSERT INTO salesorders
(donut_order_id,date,special_handling_note)
VALUES( 0000001,"2018-04-22","Please include plates and napkins");
CREATE TABLE salesorderslineitem
(
donut_order_id INT(10) NOT NULL,
donut_id INT(10) NOT NULL,
qty INT(10) NOT NULL,
PRIMARY KEY (donut_order_id, donut_id),
FOREIGN KEY (donut_order_id) REFERENCES salesorders(donut_order_id),
FOREIGN KEY (donut_id) REFERENCES donuts(donut_id)
);
INSERT INTO salesorderslineitem
(qty)
VALUES (10);
CREATE TABLE donuts
(donut_id INT(10) NOT NULL AUTO_INCREMENT,
name VARCHAR(30),
description VARCHAR(50),
unit_price DECIMAL(8,3),
PRIMARY KEY (donut_id)
);
INSERT INTO donuts
(name,description,unit_price)
解决方案
我已经解决了你所有的问题。
这是一个有效的 SQLFiddle。http://sqlfiddle.com/#!9/5071d0
第一个问题是尚未CREATE Statement
为Customers
表定义,并试图CREATE TABLE salesorders
在下一行的语句中向这个不存在的表添加一个 FOREIGN KEY
FOREIGN KEY (customer_id) REFERENCES customers(customer_id)
为了解决这个问题,我写了CREATE 语句CREATE TABLE Customers
之前的部分。SalesOrders
那只是1个问题。您还在SalesOrders
表格之前创建Donuts
表格并尝试添加FOREIGN KEY
约束。
最后,您的表中没有任何记录Donuts
,所以我为您创建了一个Jelly Donut
:)
为了完整起见,下面发布了 SQLFiddle 代码。
CREATE TABLE customers (
customer_id INT(10) NOT NULL AUTO_INCREMENT,
customer_name VARCHAR(100) NOT NULL,
PRIMARY KEY (customer_id)
);
CREATE TABLE donuts (
donut_id INT(10) NOT NULL AUTO_INCREMENT,
name VARCHAR(30),
description VARCHAR(50),
unit_price DECIMAL(8,3),
PRIMARY KEY (donut_id) );
INSERT INTO donuts (donut_id,name,description,unit_price)
VALUES (1,"Jelly Donut","Delicious Donut filled with Raspberry Jelly inside",1.99);
CREATE TABLE salesorders (
donut_order_id INT(10) NOT NULL AUTO_INCREMENT,
customer_id INT, date DATETIME,
special_handling_note TEXT,
PRIMARY KEY (donut_order_id),
FOREIGN KEY (customer_id) REFERENCES customers(customer_id) );
INSERT INTO salesorders ( donut_order_id,date,special_handling_note )
VALUES( 0000001,"2018-04-22","Please include plates and napkins" );
CREATE TABLE salesorderslineitem (
donut_order_id INT(10) NOT NULL,
donut_id INT(10) NOT NULL, qty INT(10) NOT NULL,
PRIMARY KEY (donut_order_id, donut_id),
FOREIGN KEY (donut_order_id)
REFERENCES salesorders(donut_order_id),
FOREIGN KEY (donut_id) REFERENCES donuts(donut_id) );
INSERT INTO salesorderslineitem (donut_order_id,donut_id, qty) VALUES (0000001,1, 12);
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