SQL 교차 조인

1 개요

SQL cross join

SQL 교차 조인, 크로스 조인

2 예시 1

SELECT * FROM employee

SELECT * FROM department

SELECT *
FROM employee CROSS JOIN department

SELECT *
FROM employee, department

3 예시 2

CREATE TABLE Sales (Date date, CountryID int(11), Units int(11));
INSERT INTO Sales (Date, CountryID, Units) VALUES
	('2020-01-01', 1, 40),
	('2020-01-02', 1, 25),
	('2020-01-03', 3, 30),
	('2020-01-04', 4, 35);

CREATE TABLE Countries (ID int(11), Country varchar(16));
INSERT INTO Countries (ID, Country) VALUES
	(1, 'USA'),
	(2, 'Canada');

SELECT Sales.*, Countries.Country
FROM Sales CROSS JOIN Countries

4 같이 보기

• 곱집합
• SQL 조인
• SQL 전체 조인

5 참고

• 영어 위키백과 "Join (SQL)#Cross join"