Monday, May 24, 2010

Arrange a Column of Database Table

This section provides an example with code that arrange the records of database table in descending order. The descending order provides a way for arranging records from largest to smallest in a sequence like: 100,85,45,12,......... See detail information below:

Description of program:

First of all in this program we are will establish the connection with MySQL database. As soon as the connection gets established it takes a table name and column name which we want to see in descending order. If the data gets arranged in descending order then it we are going to display the message "Descending order of given column:"........... otherwise shows a message "SQL statement is not executed!".

Description of code:

SELECT col_name FROM table_name ORDER BY col_name DESC:
This query helps us to arrange the records of database table in descending order.

The SELECT specifies the table columns that are retrieved.
The FROM clause tells from where the tables has been accessed.
The ORDER BY clause needed to us whenever, we want to sort the data of any column of the table.
The DESC clause provides the facility to arrange the data in descending order (decrease order).

Here is the code of program:

import java.io.*;
import java.sql.*;

public class ColumnDescOrder{
public static void main(String[] args) {
System.out.println("Descending order 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();
BufferedReader bf = new BufferedReader(new InputStreamReader(System.in));
System.out.println("Enter table name:");
String table = bf.readLine();
System.out.println("Enter column name which have to see descending order:");
String col_name = bf.readLine();
ResultSet res = st.executeQuery
("SELECT "+col_name+" FROM "+table+" ORDER BY "+col_name+" DESC");
System.out.println("Descending order of given column:");
while (res.next()){
int col = res.getInt(1);
System.out.println(col);
}
}
catch (SQLException s){
System.out.println("SQL statement is not executed!");
}
}
catch (Exception e){
e.printStackTrace();
}
}
}
Download this example.

Output of program:

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

C:\vinod\jdbc\jdbc\jdbc-mysql>java ColumnDescOrder
Descending order example!
Enter table name:
emp_sal
Enter column name which have to see descending order:
Emp_sal
Descending order of given column:
10000
8000
5000
4500
600

No comments:

Post a Comment