Chapter 7, Problem 3RQ

What is a cross join? Give an example of its syntax.

Program Plan Intro

Join:

Join is a relational operation, which combines the data from two or more tables into single table or view, then that is called as Join.

Explanation of Solution

CROSS join:

• It is a type of join operation that performs Cartesian product of two tables.
• That is, it produces a result set in which the rows from first table are multiplied with the rows from second table.

Syntax:

SELECT * FROM table_1 CROSS JOIN table_2;

Example:

Table creation:

Creating table 1:

CREATE TABLE table_1 (Item_ID int, Item_Name varchar(10), Company_ID int primary key);

Creating table 1:

CREATE TABLE table_2 (Company_ID int references table_1, Company_Name varchar(10), Company_city varchar(10));

Inserting values:

Inserting values to table 1:

INSERT INTO table_1 values (1, "Pancakes", 101);

INSERT INTO table_1 values (2, "Rice", 109);

INSERT INTO table_1 values (3, "Cakes", 106);

Inserting values to table 1:

INSERT INTO table_2 values (106, "AAA", "ZZZ");

INSERT INTO table_2 values (109, "BBB", "YYY");

Query using “CROSS JOIN”:

SELECT * FROM table_1 CROSS JOIN table_2;

Sample Output

Screenshot of the result: