Join tables with the NATURAL LEFT JOIN operation
This section describes the NATURAL LEFT JOIN operation
and how to retrieve data through it. In this operation we are going to retrieve data according
to match the field name of another tables.
NATURAL LEFT JOIN: In this operation both tables
are merged to each other according to common fields but the priority is given to
the first table in database.
Description of program:
In this program we are going to establish the connection with MySQL database
by using the JDBC driver, after that we will join two tables through the help of NATURAL
LEFT JOIN operation. It retrieves data on the specific field name that matches
in both tables.
Description of code:
SELECT *FROM employee NATURAL LEFT JOIN Emp_sal:
Above code retrieves all data that matches in both tables on the basis of
Emp_name field.
Here is the code of program:
import java.sql.*;
public class NatLeftJoinTable{
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"+" NATURAL LEFT JOIN "+"Emp_sal");
//Natural Left 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 NatLeftJoinTable.java
C:\vinod\jdbc\jdbc\jdbc-mysql>java NatLeftJoinTable
Natural Left Join Tables Example!
Emp_name Emp_ed
Emp_sal
santosh 2
4500
deepak 10
0
Aman 13
8000 |
|
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