Getting started with JDBC

The JDBC Application involves opening database connection, SQL Query execution and result display.

Creating JDBC Application:

A JDBC application has steps below:

• Packages Import
• JDBC driver Register
• Open Connection
• Query Execution
• Result set data Extraction
• Environment Clean up

Example:

Below code can be executed once the database and environment setup is done in previous chapter. Save the example as JavaFirstExample.java compile and run:

//STEP 1. Packages Import
import java.sql.*;

public class JavaFirstExample{

   static final String JDBC_DRIVER = "com.mysql.jdbc.Driver";  
   static final String DB_URL = "jdbc:mysql://localhost/Users";
   static final String USER = "my_user";
   static final String PASS = "my_password";
   public static void main(String[] args) {
   Connection connn = null;
   Statement stmt1 = null;
   try{
      //JDBC driver Register
      Class.forName("com.mysql.jdbc.Driver");

      //Open Connection
      connn = DriverManager.getConnection(DB_URL,USER,PASS);

      //Query Execution
      Stmt1 = connn.createStatement();
      String sql1;
      sql1 = "SELECT user_id, user_first, user_last, user_age FROM USER";
      ResultSet rs = stmt.executeQuery(sql1);

      //STEP 5: Result set data Extraction
      while(rs.next()){
         int id_1  = rs.getInt("user_id");
         int age_1 = rs.getInt("user_age");
         String first_1 = rs.getString("user_first");
         String last_2 = rs.getString("user_last");

         //Output results
         System.out.print("USER System ID: " +user_id);
         System.out.print(",USER Current Age: " +user_age);
         System.out.print(",USER First name: " +user_first);
         System.out.println(",USER Last name: " +user_last);
      }
      //STEP 6:  environment Clean-up
      rs.close();
      stmt1.close();
      connn.close();
   }catch(SQLException se){
      se.printStackTrace();
   }catch(Exception e){
      e.printStackTrace();
   }finally{
 
      try{
         if(stmt1!=null)
            stmt1.close();
      }catch(SQLException se2){
      }
      try{
         if(connn!=null)
            connn.close();
      }catch(SQLException se){
         se.printStackTrace();
      }
   }

}
}

Compile example as below:

C:\>javac JavaFirstExample.java

C :\>

Run JavaFirstExample results as shown:

C:\>java JavaFirstExample 

USER System ID: 100, USER Current Age: 5, USER First name: Yuvraaj, USER Last Name: C
USER System ID: 101, USER Current Age: 2, USER First name: Nimrit,USER Last Name: K