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.

Cross Join Tables in a Specific Database

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

Tutorials

  1. Mapping MySQL Data Types in Java
  2. Connecting to a MySQL Database in Java
  3. Creating a Database in MySQL
  4. Creating a Database Table
  5. Creating a MySQL Database Table to store Java Types
  6. Description of Database Table
  7. Deleting a Table from Database
  8. Retrieving Tables from a Database
  9. Inserting values in MySQL database table
  10. Retrieving All Rows from a Database Table
  11. Adding a New Column Name in Database Table
  12. Change Column Name of a Table
  13. Make Unique Column in Database Table
  14. Remove Unique Column in Database Table
  15. Arrange a Column of Database Table
  16. Arrange a Column of Database Table
  17. Sum of Column in a Database Table
  18. Deleting All Rows from a Database Table
  19. Delete a Specific Row from a Database Table
  20. Delete a Column from a Database Table
  21. Join tables in the specific database
  22. Join tables with the NATURAL LEFT JOIN operation
  23. Join tables with the NATURAL RIGHT JOIN operation
  24. Cross Join Tables in a Specific Database
  25. Prepared Statement Set Object
  26. Statement Batch Update
  27. Prepared Statement With Batch Update
  28. Select Records Using Prepared Statement
  29. Update Records using Prepared Statement
  30. Inserting Records using the Prepared Statement
  31. Count Records using the Prepared Statement
  32. Deleting Records using the Prepared Statement
  33. Using the Prepared Statement Twice
  34. Set Data Types by using Prepared Statement
  35. Set byte, short and long data types by using the Prepared Statement
  36. Prepared Statement Set Big Decimal
  37. Set Date by using the Prepared Statement
  38. Set Time by using the Prepared Statement
  39. Set Timestamp by using the Prepared Statement
  40. Copy Table in a MySQL Database