I have been reading through this forum trying to find the right things to solve my question but I cannot find any answers. I have tweaked my code so much to make sure that the issue is really with adding a foreign key.
My tables are created before I made the foreign key and they are not referencing each out. What is going on?
CREATE TABLE Customer (
CustomerID integer NOT NULL PRIMARY KEY,
LName varchar(200),
FName varchar(200),
StreetAdd varchar(200),
City varchar(100),
State varchar(100),
Zip integer,
Phone bigint
);
CREATE TABLE Donut (
DonutID integer NOT NULL PRIMARY KEY,
Name varchar(100),
Description varchar(200),
UnitPrice float(2)
);
CREATE TABLE Invoice(
Quantity smallint,
OrderID integer,
DonutID integer,
FOREIGN KEY (OrderID) REFERENCES DOrder(OrderID),
FOREIGN KEY (DonutID) REFERENCES Donut(DonutID)
);
CREATE TABLE DOrder (
OrderID integer NOT NULL,
OrderDat integer,
Notes varchar(400),
CustomerID integer,
PRIMARY KEY(OrderID),
FOREIGN KEY (CustomerID) REFERENCES Customer(CustomerID)
);
Related
I am trying to figure out what is wrong with my syntax here. I feel like I have matched the examples I have found over the internet... but something must be amiss. Here is the code I am using. I keep getting the error code "cannot add Foreign Key constraint" when trying to run the build the schema.
CREATE TABLE Employe (
employee_id INT PRIMARY KEY,
first_name VARCHAR(30),
last_name VARCHAR(30),
hire_date DATE,
job_title VARCHAR(30),
shop_id INT,
FOREIGN KEY (shop_id) REFERENCES Coffee_Shop(shop_id)
);
CREATE TABLE Coffee_Shop (
shop_id INT PRIMARY KEY,
shop_name VARCHAR(50),
state CHAR(2),
);
CREATE TABLE Coffee (
coffee_id INT PRIMARY KEY,
shop_id INT,
supplier_id INT,
coffee_name VARCHAR(30),
price_per_pound NUMERIC(5,2),
FOREIGN KEY (shop_id) REFERENCES Coffee_Shop(shop_id),
FOREIGN KEY (supplier_id) REFERENCES Supplier(supplier_id)
);
CREATE TABLE Supplier (
supplier_id INT PRIMARY KEY,
company_name VARCHAR(50),
country VARCHAR(30),
sales_contact_name VARCHAR(60),
email VARCHAR(50) NOT NULL,
);
I just need to figure out what part of my foreign key is incorrectly defined. I know it normally results from an improperly defined primary key, but cannot seem to find where I messed up.
Thanks for your help
You are referencing a KEY that is not set up yet. SQL is linear, so the code gets executed line-by-line and cannot reference future lines (in most cases)
Create your tables in this order:
CREATE TABLE Coffee_Shop (
shop_id INT PRIMARY KEY,
shop_name VARCHAR(50),
state CHAR(2),
);
CREATE TABLE Supplier (
supplier_id INT PRIMARY KEY,
company_name VARCHAR(50),
country VARCHAR(30),
sales_contact_name VARCHAR(60),
email VARCHAR(50) NOT NULL,
);
CREATE TABLE Employe (
employee_id INT PRIMARY KEY,
first_name VARCHAR(30),
last_name VARCHAR(30),
hire_date DATE,
job_title VARCHAR(30),
shop_id INT,
FOREIGN KEY (shop_id) REFERENCES Coffee_Shop(shop_id)
);
CREATE TABLE Coffee (
coffee_id INT PRIMARY KEY,
shop_id INT,
supplier_id INT,
coffee_name VARCHAR(30),
price_per_pound NUMERIC(5,2),
FOREIGN KEY (shop_id) REFERENCES Coffee_Shop(shop_id),
FOREIGN KEY (supplier_id) REFERENCES Supplier(supplier_id)
);
So I don't know why i cant add the foreign constraint in the table ORDER_LINE, i made sure all the types are correct. Please help, it keeps on giving me the error
Error Code: 1215. Cannot add foreign key constraint
CREATE TABLE IF NOT EXISTS Customer (
Customer_ID int NOT NULL AUTO_INCREMENT,
Customer_Name VARCHAR(50) NOT NULL,
Customer_Age INT UNIQUE,
Customer_Address VARCHAR(255),
Customer_City VARCHAR(255),
Customer_State VARCHAR(50),
Customer_Zip VARCHAR(20),
PRIMARY KEY(Customer_ID)
);
CREATE TABLE IF NOT EXISTS Sales_order (
Order_ID int AUTO_INCREMENT,
Order_date DATE,
Customer_ID int,
PRIMARY KEY(Order_ID),
FOREIGN KEY(Customer_ID) REFERENCES Customer(Customer_ID) ON DELETE
CASCADE
);
CREATE TABLE IF NOT EXISTS Products (
Product_ID int AUTO_INCREMENT,
Product_Description VARCHAR(255),
Product_Finish VARCHAR(50),
Standard_Price DECIMAL,
Product_Line_ID INT,
PRIMARY KEY(Product_ID)
);
CREATE TABLE IF NOT EXISTS ORDER_LINE (
Order_ID int,
Product_ID int,
Ordered_Quantity int,
PRIMARY KEY(Order_ID, Product_ID),
FOREIGN KEY(Order_ID) REFERENCES Sales_order(Order_ID) ON DELETE SET NULL,
FOREIGN KEY(Product_ID) REFERENCES Products(Product_ID)
);
This might be because primary key columns are made NOT NULL, so your ON DELETE SET NULL is trying to set an invalid value.
EDIT: In fact, I just tested and that does seem to be the issue -- it creates the table if I remove either the SET NULL or the primary key.
ER Diagram -
Hi Everyone , i started learning Database few weeks ago , and had this exercise today . I have to convert E-R diagram to SQL . Can someone check my code if its ok ?
I am confused at part of weak entity DRUG .
create database Ilacet
go
use ilacet
go
--definimi i tabelave
create table Patient
(
ssn varchar(10),
phy_ssn varchar(10),
age tinyint,
name varchar(20) not null,
address varchar(25),
constraint SSN_PK primary key (ssn),
constraint PHY_FK foreign key (phy_ssn) references Doctor
)
go
create table Doctor
(
phy_ssn varchar(10),
speciality varchar(20) not null,
name varchar(20) not null,
exp_year tinyint(2),
constraint PHY_SSN_PK primary key (phy_ssn)
)
go
create table Pharmacy
(
name varchar(20),
address varchar(20) not null,
phone_number varchar(20) not null,
constraint NAME_PK primary key (name)
)
go
create table Pharm_co
(
pname varchar(20),
phone_num varchar(15) not null,
constraint PNAME_PK primary key(pname)
)
go
create table Drug
(
trade_name varchar(20),
pname varchar(20),
formula varchar(20),
constraint D_PK primary key(trade_name,pname),
constraint DP_S foreign key (pname) references Pharm_co
)
go
create table Prescription
(
ssn varchar(10),
phy_ssn varchar(20),
trade_name varchar(20),
pname varchar(10)
data date,
quantity integer,
constraint PK_PK primary key(ssn,phy_ssn,trade_name,pname),
constraint Pn_F foreign key (ssn) references Patient,
constraint DO_F foreign key(phy_ssn) references Doctor,
constraint PO_F foreign key(pname) references Pharm_co,
constraint DR_F foreign key(trade_name) references Drug
)
go
create table Contract
(
name varchar(20),
pname varchar(20),
start_date date,
end_date date,
text varchar(15),
supervisor varchar(15),
constraint PN_PK primary key(name,pname)
constraint NAME_P foreign key (name) references Pharmacy,
constraint P_N foreign key(pname)references Pharm_co
)
go
create table Sell
(
name varchar(20),
trade_name varchar(20)
pname varchar(20),
price integer,
constraint PK_KK primary key(name,trade_name,pname) ,
constraint Pharmacy_name foreign key (name) references Pharmacy,
constraint Drug_name foreign key(trade_name)references Drug,
constraint Pharm_id foreign key(pname) references Pharm_co
)
go
I'm trying to create a database, i have one table in my database and want to add the other one.
The table i have:
create table department(
dept_name varchar(20),
building varchar(20) not null,
budget numeric(8,2),
primary key (dept_name)
)
and i want to add this table:
create table student (
ID varchar(5),
name varchar(20) not null,
dept_name varchar(20),
tot_cred numeric(3,0),
primary key (ID),
foreign key (dept_name) references department
)
But i get this error:
#1215 - Cannot add foreign key constraint
Can you guys help me with this problem?
Thanks.
Your 2nd table should be-
create table student (
ID varchar(5),
name varchar(20) not null,
dept_name varchar(20),
tot_cred numeric(3,0),
primary key (ID),
foreign key (dept_name) references department(dept_name)
)
Note: It will be better include dept_id as int in your parent table and create reference it in 2nd table to get better performance.
create tables as per below-
create table department(
dept_id int auto_increment,
dept_name varchar(20),
building varchar(20) not null,
budget numeric(8,2),
primary key (dept_id)
);
create table student (
ID varchar(5),
name varchar(20) not null,
dept_it int,
tot_cred numeric(3,0),
primary key (ID),
foreign key (dept_id) references department(dept_id)
)
CREATE TABLE postcodes (
postcode_ID INT NOT NULL,
location VARCHAR(50),
PRIMARY KEY (postcode_ID)
);
CREATE TABLE countries (
country_ID INT NOT NULL AUTO_INCREMENT,
country_name VARCHAR(50),
PRIMARY KEY (country_ID)
);
CREATE TABLE suppliers (
supplier_ID INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
supplier_name VARCHAR(50),
supplier_forename VARCHAR(50),
supplier_phonenumber VARCHAR(20),
supplier_address VARCHAR(50),
supplier_postcode INT,
supplier_country INT,
FOREIGN KEY (supplier_postcode) REFERENCES postcode(postcode_ID),
FOREIGN KEY (supplier_country) REFERENCES countries(country_ID)
) ;
Typo:
CREATE TABLE postcodes (
^----plural
FOREIGN KEY (supplier_postcode) REFERENCES postcode(postcode_ID),
^----no S, singular
You're trying to reference a table which doesn't exist.