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Arithmetic Operation using AWT Frame with Event Delegation

import java.awt.Button;
import java.awt.FlowLayout;
import java.awt.Frame;
import java.awt.Label;
// author : www.raviroza.com
// date   : 27-Jan-2023, 8.25 am
import java.awt.TextField;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

public class ArithmaticOperation 
extends Frame
implements ActionListener
{
	Label l1,l2,lblResult;
	TextField txtNo1, txtNo2;
	Button btnAdd, btnSub, btnMul, btnDiv;
	
	public ArithmaticOperation() {
		// TODO Auto-generated constructor stub
		l1 = new Label("enter number 1 : ");
		l2 = new Label("enter number 2 : ");
		lblResult = new Label("0");
		
		txtNo1 = new TextField(3);
		txtNo2 = new TextField(3);
		
		btnAdd = new Button("+");
		btnSub = new Button("-");
		btnMul = new Button("*");
		btnDiv = new Button("/");
		
		setLayout(new FlowLayout());
		add(l1);  add(txtNo1);
		add(l2);  add(txtNo2);
		
		add(lblResult);
		
		add(btnAdd);  add(btnSub);
		add(btnMul);  add(btnDiv);
		
		btnAdd.addActionListener(this);
		btnSub.addActionListener(this);
		btnMul.addActionListener(this);
		btnDiv.addActionListener(this);
		
			
		setSize(500, 500);
		//validate();
		
		setVisible(true);
	}	
	public void actionPerformed(ActionEvent e) 
	{
		int a = Integer.parseInt(txtNo1.getText());
		int b = Integer.parseInt(txtNo2.getText());
		int c = 0;
		if(e.getSource() == btnAdd)		
		{
				c = a + b;			
		}		
		else if(e.getSource() == btnSub)
		{
				c = a - b;			
		}
		else if(e.getSource() == btnMul)
		{
				c = a * b;			
		}
		else if(e.getSource() == btnDiv)
		{
				c = a / b;			
		}							
		lblResult.setText ( Integer.toString(c));
	}
	public static void main(String[] args) 
	{
		new ArithmaticOperation();
	}
}

JDBC Callable Statement Example

JDBC Callable Statement Theory

  • CallableStatement interface is used to call the stored procedures or functions.
  • We can have business logic on the database by the use of stored procedures and functions that will make the performance better because they are precompiled.
  • For example we need to retrieve the age of the student based on birth date, one may create a function that receives date as INPUT and returns age of the student as the OUTPUT.

JDBC Prepared Statement Example

  • The main feature of a PreparedStatement object is that, unlike a Statement object, it is given a SQL statement when it is created.
  • The advantage to this is that in most cases, this SQL statement is sent to the DBMS right away, where it is compiled.
  • As a result, the PreparedStatement object contains not just a SQL statement, but a SQL statement that has been precompiled.
  • This means that when the PreparedStatement is executed, the DBMS can just run the PreparedStatement SQL statement without having to compile it first.

JDBC with MS Access Database in Java 8

  • Since JDK 8, Java does not support ODBC driver for JDBC connectivity.
  • MS Access does not provide driver for JDK 8, therefore third party driver which is “UCanAccess” can be used to connect with MS Access database.
  • Download UCanAccess Driver.
  • Following is the way to connect with MSAccess database.
  • Please create the following table in Access : Student (Sno number, Sname Text(50), Scity(50))
import java.sql.*;

public class Main {

	public static void main(String[] args) throws Exception
	{		
		Class.forName("net.ucanaccess.jdbc.UcanaccessDriver");
		Connection conn = 
			DriverManager.getConnection("jdbc:ucanaccess://C:/raviroza/ravi.mdb");			
		String Q = "Insert into Student values (101,'raviroza.com','world wide web')";
		if(conn.createStatement().executeUpdate(Q)>0)
		{
			System.out.println("Recored added");
		}
	}
}

What is JDBC Prepared Statement?

  • Sometimes it is more convenient to use a PreparedStatement object for sending SQL statements to the database. This special type of statement is derived from the more general class, Statement, that you already know.
  • If you want to execute a Statement object many times, it usually reduces execution time to use a PreparedStatement object instead.
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