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500

Chapter 18 JDBC and Database Connection Pooling

Listing 18.18 PreparedStatements.java (continued)

  public static void doRawQueries(Connection conn,

                                  boolean print) {

    try {

      String queryFormat =

        "SELECT lastname FROM employees WHERE salary > ";

      Statement statement = conn.createStatement();

      long startTime = System.currentTimeMillis();

      for(int i=0; i<40; i++) {

        ResultSet results =

          statement.executeQuery(queryFormat + (i*5000));

        if (print) {

          showResults(results);

        }

      }

      long stopTime = System.currentTimeMillis();

      double elapsedTime = (stopTime   startTime)/1000.0;

      System.out.println("Executing raw query " +

                         "40 times took " +

                         elapsedTime + " seconds.");

    } catch(SQLException sqle) {

      System.out.println("Error executing query: " + sqle);

    }

  } 

  private static void showResults(ResultSet results)

      throws SQLException {

    while(results.next()) {

      System.out.print(results.getString(1) + " ");

    }

    System.out.println();

  }

  private static Connection getConnection(String driver,

                                          String url,

                                          String username,

                                          String password) {

    try {

      Class.forName(driver);

      Connection connection =

        DriverManager.getConnection(url, username, password);

      return(connection);

    } catch(ClassNotFoundException cnfe) {

      System.err.println("Error loading driver: " + cnfe);

      return(null);

    } catch(SQLException sqle) {

      System.err.println("Error connecting: " + sqle);

      return(null);

    }

  }

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