VSA prve cviko

/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
package javaapplication1;
import java.sql.*;
/**
 *
 * @author xpodluckyf
 */
public class JavaApplication1 {
     // JDBC driver name and database URL
         static final String JDBC_DRIVER = "org.apache.derby.jdbc.ClientDrive";
         static final String DB_URL = "jdbc:derby://localhost:1527/sample";

    //  Database credentials
         static final String USER = "app";
         static final String PASS = "app";


       /**
     * @param args the command line arguments
     */
    public static void main(String[] args) throws ClassNotFoundException, SQLException  {
       //STEP 3: Open a connection
       Statement stmt = null;
       Statement stmt1 = null;
       Connection conn = null;
      try{ Class.forName("org.apache.derby.jdbc.ClientDriver");
       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 * FROM KNIHA";
       ResultSet rs = stmt.executeQuery(sql);

        stmt1 = conn.createStatement();
        String sql2 = "UPDATE KNIHA set cena=cena*0.9 where cena > 200";
        stmt1.executeUpdate(sql2);

//STEP 5: Extract data from result set
         while(rs.next()){
         //Retrieve by column name
         String nazov  = rs.getString("nazov_knihy");
         int cena = rs.getInt("cena");

         //Display values
         System.out.print("Nazov: " + nazov);
         System.out.print(", Cena: " + cena);

      }
         System.out.println();
      //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!");

    }

}