JAVA PROGRAMMING – ACCESSING DATABASES USING JDBC

You can access databases using JAVA. The special feature available in Java for this purpose is Java Database Connectivity (JDBC).

You have to create a database in MS Access or Oracle or MySQL or any other database management system. Then give an ODBC name for your database.

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// The following example illustrates how to display a table in
// JAVA using
// Java Database Connectivity (JDBC).
// Before running the program, create a table
// named as BOOKS in Oracle 9i.
// Declare the database giving ODBC Name bk.
// User Name is kt.
// Password is kt.
// Save File as MyTable.java
// Assuming that your java bin directory is C:\java\bin
// Compile the file using
// C:\java\bin javac MyTable.java
// to create MyTable.class file.
// Execute the program using
// C:\java\bin java MyTable.

import java.sql.*;
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.util.*;

public class MyTable extends JFrame {
private Connection connection;
private JTable table;

public MyTable()
{
String url="jdbc:odbc:bk";
String username ="kt";
String password="kt";

try {
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
connection=DriverManager.getConnection(url,username,password);
}

catch(ClassNotFoundException cnfex) {
System.err.println("Failed to load JDBC/ODBC driver.");
cnfex.printStackTrace();
System.exit(1);
}

catch( SQLException sqlex ) {
System.err.println("Unable to connect");
sqlex.printStackTrace();
}

getTable();

setSize(450,150);
show();
}

private void getTable()
{
Statement statement;
ResultSet resultSet;

try {
String query = "SELECT * FROM BOOKS";
statement = connection.createStatement();
resultSet=statement.executeQuery(query);
displayResultSet(resultSet);

statement.close();
}

catch ( SQLException sqlex) {
sqlex.printStackTrace();
}
}

private void displayResultSet(ResultSet rs) throws SQLException
{
boolean moreRecords=rs.next();
if (!moreRecords) {
JOptionPane.showMessageDialog(this,"ResultSet contained no records");
setTitle("No records to display");
return;
}

setTitle("Authors table from Books");

Vector columnHeads=new Vector();
Vector rows=new Vector();

try{
ResultSetMetaData rsmd=rs.getMetaData();

for ( int i=1; i<=rsmd.getColumnCount();++i)
columnHeads.addElement(rsmd.getColumnName(i));

do{
rows.addElement(getNextRow(rs,rsmd));
} while (rs.next());

table=new JTable(rows,columnHeads);
JScrollPane scroller=new JScrollPane(table);
getContentPane().add(scroller,BorderLayout.CENTER);
validate();
}

catch(SQLException sqlex) {
sqlex.printStackTrace();
}
}

private Vector getNextRow(ResultSet rs,ResultSetMetaData rsmd) throws SQLException
{
Vector currentRow= new Vector();

for (int i=1; i<=rsmd.getColumnCount();++i)
switch(rsmd.getColumnType(i)) {
case Types.VARCHAR:
currentRow.addElement(rs.getString(i));
break;
case Types.DECIMAL:
currentRow.addElement(new Long(rs.getLong(i)));
break;
default:
System.out.println("Type was: "+rsmd.getColumnTypeName(i));
}
return currentRow;
}

public void shutDown()
{
try{
connection.close();
}
catch(SQLException sqlex) {
System.err.println("Unable to disconnect");
sqlex.printStackTrace();
}
}

public static void main(String args[])
{
final MyTable app=new MyTable();

app.addWindowListener(
new WindowAdapter() {
public void windowClosing(WindowEvent e)
{
app.shutDown();
System.exit(0);
}
}
);
}
}



// For more details see Java How To Program