sql bai 11

 USE SAMPLEDATABASE;

DROP TABLE IF EXISTS Customers;

DROP TABLE IF EXISTS Countries;

CREATE TABLE Countries (

ID INT PRIMARY KEY auto_increment,

    Country VARCHAR(10)

);

CREATE TABLE Customers (

CustomerID INT PRIMARY KEY,

    CustomerName VARCHAR(30),

    ContactName VARCHAR(30),

    Address VARCHAR(30),

    City VARCHAR(10),

    PostalCode VARCHAR(10),

    CountryID INT,

    FOREIGN KEY (CountryID) REFERENCES Countries(ID)

);

INSERT into Countries (Country) VALUES ('VIETNAM'), ('UNITED'), ('CHINA'), ('SING');

INSERT INTO Customers 

VALUES (2, "Alfreds Futterkiste", "Maria Anders", "Obere Str. 57", "Berlin", "f12209", 3),

(3, "A Futterkiste", "Maria Anders", "Obere Str. 57", "Berlin", "f12209", 3),

(4, "freds Futterkiste", "Maria Anders", "Obere Str. 57", "Berlin", "f12209", 1),

(5, "Ds Futterkiste", "Maria Anders", "Obere Str. 57", "Berlin", "f12209", 2),

(6, "Dr Thach", "Maria Anders", "Obere Str. 57", "Berlin", "f12209", null);

SELECT * FROM Customers

RIGHT JOIN Countries

ON Customers.CountryID = Countries.ID

UNION

SELECT * FROM Customers

LEFT JOIN Countries

ON Customers.CountryID = Countries.ID