//STEP 1. Import required packages
import java.sql.*;

public class FirstExample {
   // JDBC driver name and database URL
   static final String JDBC_DRIVER = "org.postgresql.Driver";
   static final String DB_URL = "jdbc:postgresql://localhost/postgres";

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

   public static void main(String[] args) {
   Connection conn = null;
   Statement stmt = null;
   try{
      //STEP 2: Register JDBC driver
      Class.forName("org.postgresql.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;
      String sql2,sql3,sql4;
      sql3="BEGIN WORK";
      sql2="LOCK TABLE public.rawinput";
      sql4="END WORK";
     // /*
      //stmt.executeQuery(sql3);
      //stmt.executeQuery(sql2);
      //stmt.executeQuery(sql4);

      sql = "SELECT product_id FROM public.rawinput";
      //ResultSet rs = stmt.executeQuery("");
      ResultSet rs = stmt.executeQuery(sql);

      //STEP 5: Extract data from result set
      while(rs.next()){
         //Retrieve by column name
         int id  = rs.getInt("product_id");


         //Display values
         System.out.println("ID: " + id);

      }


      //extra test





      //einde extra test

      //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