JDBC sample code

This tutorial provides an example of how to create a simple JDBC application. Demonstrates how to open a database connection, execute an SQL query, and display the results.

All of the steps mentioned in this template example are described in the following sections of this tutorial.

Create a JDBC application:

There are six steps involved in building a JDBC application:

Import packet .   You need to include packages that contain JDBC classes that you need to program your database. Most of the time, use & cake; Import the Java. SQL. *   That's it.

Register the JDBC driver .   The driver needs to be initialized and a communication channel can be opened with the database.

Open the connection .   You need to use the DriverManager. GetConnection ()   Method creates a Connection object that represents a physical Connection to the database.

Execute the query .   You need to create and submit an SQL statement to the database using the object type declaration.

Extract data from the result set .   Requires that the appropriate method about resultset.getxxx () be used to retrieve the data for the ResultSet.

Clean up the environment .   You need to explicitly close all database resources relative to the JVM's garbage collection.

Sample code:
The example of this example can be used as a template where you need to build a JDBC application.

Based on the environment and database installed in the previous section do this sample code has been written.

Copy the following example, firstexample.java, compile and run as follows:

//STEP 1. Import required packages
import java.sql.*;
public class FirstExample {
   // JDBC driver name and database URL
   static final String JDBC_DRIVER = "com.mysql.jdbc.Driver";  
   static final String DB_URL = "jdbc:mysql://localhost/EMP";
   //  Database credentials
   static final String USER = "username";
   static final String PASS = "password";

   public static void main(String[] args) {
   Connection conn = null;
   Statement stmt = null;
   try{
      //STEP 2: Register JDBC driver
      Class.forName("com.mysql.jdbc.Driver");
      //STEP 3: Open a connection
      System.out.println("Connecting to database...");
      conn = DriverManager.getConnection(DB_URL,USER,PASS);
      //STEP 4: Execute a query
      System.out.println("Creating statement...");
      stmt = conn.createStatement();
      String sql;
      sql = "SELECT id, first, last, age FROM Employees";
      ResultSet rs = stmt.executeQuery(sql);
      //STEP 5: Extract data from result set
      while(rs.next()){
         //Retrieve by column name
         int id  = rs.getInt("id");
         int age = rs.getInt("age");
         String first = rs.getString("first");
         String last = rs.getString("last");
         //Display values
         System.out.print("ID: " + id);
         System.out.print(", Age: " + age);
         System.out.print(", First: " + first);
         System.out.println(", Last: " + last);
      }
      //STEP 6: Clean-up environment
      rs.close();
      stmt.close();
      conn.close();
   }catch(SQLException se){
      //Handle errors for JDBC
      se.printStackTrace();
   }catch(Exception e){
      //Handle errors for Class.forName
      e.printStackTrace();
   }finally{
      //finally block used to close resources
      try{
         if(stmt!=null)
            stmt.close();
      }catch(SQLException se2){
      }// nothing we can do
      try{
         if(conn!=null)
            conn.close();
      }catch(SQLException se){
         se.printStackTrace();
      }//end finally try
   }//end try
   System.out.println("Goodbye!");
}//end main
}//end FirstExample

Now compile the above example as follows:

C:>javac FirstExample.java
C:>

When you run FirstExample, it produces the following results:

C:>java FirstExample
Connecting to database...
Creating statement...
ID: 100, Age: 18, First: Zara, Last: Ali
ID: 101, Age: 25, First: Mahnaz, Last: Fatma
ID: 102, Age: 30, First: Zaid, Last: Khan
ID: 103, Age: 28, First: Sumit, Last: Mittal
C:>