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Cross Join Tables in a Specific Database

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This section introduces you to the cross join between two tables. The cross join operation retrieves data between two tables as a Cartesian product of set theory in mathematics.

Cross Join Tables in a Specific Database

     

This section introduces you to the cross join between two tables. The cross join operation retrieves data between two tables as a Cartesian product of set theory in mathematics. Each row will get multiplied by other rows. If one table has three rows and the second row has two rows, then the cartesian of two table will be six. See brief description below:

Cross Join: This is a type of join table operation. It is a same as inner and outer join operation. The cross join is used to retrieve data from tables as Cartesian product format of set theory in mathematics. All rows are shown to be multiply by to another tables' rows.

Description of program:

First of all this program establishes the connection, after that the cross join operation will be performed between two tables. Both tables hold some specific fields and it's values. While you retrieve data in cross join format, it shows that the each row will get multiply by other rows.

Description of code:

SELECT *FROM employee, Emp_sal :
This code is used to retrieve data form both tables as Cartesian product format (multiply the field to each other).

Here is the code of program:

import java.sql.*;

public class CrossJoinTable{
  public static void main(String[] args) {
  System.out.println("Natural Left Join Tables Example!");
  Connection con = null;
  try{
  Class.forName("com.mysql.jdbc.Driver");
  con = DriverManager.getConnection
("jdbc:mysql://localhost:3306/jdbctutorial","root","root");
  try{
  Statement st = con.createStatement();
  ResultSet res = st.executeQuery
("SELECT *FROM "+"employee"+","+"Emp_sal");  //Cross Join two tables
  System.out.println("Emp_name" + "\t" + "Emp_ed" + "\t" + "Emp_sal");
  while(res.next()){
  String name = res.getString("Emp_name");
  int ed = res.getInt("Emp_ed");
  int sal = res.getInt("Emp_sal");
  System.out.println(name + "\t\t" + ed + "\t" + sal);
  }
  }
  catch (SQLException s){
  System.out.println("SQL statement is not executed!");
  }
  }
  catch (Exception e){
  e.printStackTrace();
  }
  }
} 

Download this example.

Table:- employee:   

Emp_ed Emp_name
2

10

13

santosh

deepak

Aman

Table:- Emp_sal:

Emp_name Emp_sal
Aman

santosh

8000

4500

Output of program:

C:\vinod\jdbc\jdbc\jdbc-mysql>javac CrossJoinTable.java

C:\vinod\jdbc\jdbc\jdbc-mysql>java CrossJoinTable
Natural Left Join Tables Example!
Emp_name  Emp_ed  Emp_sal
santosh   2   8000
santosh   2   4500
deepak  10  8000
deepak  10   4500
Aman  13   8000
Aman  13   4500
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Posted on: April 13, 2007

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Comments:2
sunethra shanthi
December 14, 2011
cross join

this web site is very usefull for the student.i am learn to the more information and i got a more kwolage about cross join. thank you your copprtaion.
Rajesh Maji
April 4, 2012
sql

is cross join or right join is same?
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