ResultSet Cursor and Scrollability

This section describes what is ResultSet cursor and ResultSet scrollability.

Each ResultSet object maintains a cursor (pointer) to identify the current data row. The cursor of a newly created ResultSet object is positioned before the first row. How to move the cursor is depending on the scrollability of the ResultSet.

1. Non-scrollable ResultSet - The ResultSet object type is ResultSet.TYPE_FORWARD_ONLY, the default type. Non-scrollable ResultSet supports only cursor move method:

2. Scrollable ResultSet - The ResultSet object type is ResultSet.TYPE_SCROLL_INSENSITIVE, or ResultSet.TYPE_SCROLL_SENSITIVE. Scrollable ResultSet supports a number of cursor move methods:

Here is a sample program that loops through the ResultSet rows forward only with next() method:

/* DerbyLoopResultSet.java
 * Copyright (c) HerongYang.com. All Rights Reserved.
 */
import java.sql.*;
public class DerbyLoopResultSet {
  public static void main(String [] args) {
    Connection con = null;
    try {
      con = DriverManager.getConnection("jdbc:derby://localhost/TestDB");
      Statement sta = con.createStatement();

// Catch the ResultSet object
      ResultSet res = sta.executeQuery("SELECT * FROM Profile");

// Check ResultSet's scrollability
      if (res.getType() == ResultSet.TYPE_FORWARD_ONLY) {
        System.out.println("ResultSet non-scrollable.");
      } else {
        System.out.println("ResultSet scrollable.");
      }

// Move cursor forward only with next()
      System.out.println("List of Profiles:");
      while (res.next()) {
        String firstName = res.getString("FirstName");
        String lastName = res.getString("LastName");
        System.out.println("   "+firstName+" "+lastName);
      }

// Close ResultSet
      res.close();

      sta.close();
      con.close();
    } catch (Exception e) {
      System.err.println("Exception: "+e.getMessage());
    }
  }
}

The output is listed below:

ResultSet non-scrollable.
List of Profiles:
   Janet Gates
   256d aa3f5
   8ef 466ca
   10cc ab361
   11bd 99552
   8c4 68909
   17e1 99a5d
   1ea2 480c7
   Keith Harris

Table of Contents

 About This Book

 JDBC (Java Database Connectivity) Introduction

 JDK (Java SE) Installation

 Installing and Running Java DB - Derby

 Derby (Java DB) JDBC Driver

 Derby (Java DB) JDBC DataSource Objects

 Java DB (Derby) - DML Statements

Java DB (Derby) - ResultSet Objects of Queries

 What Is ResultSet?

ResultSet Cursor and Scrollability

 ResultSet Cursor Initial Position: Before First Row

 Retrieving Column Values with getXXX() Methods

 ResultSet Default Type: Forward-only

 Scrollable ResultSet and Moving Cursor Backward

 ResultSet Objects with Update Capability

 insertRow() - Inserting New Rows through ResultSet Objects

 updateXXX() - Updating Column Values for Row Update or Insert

 deleteRow() - Deleting Rows through ResultSet Objects

 Java DB (Derby) - PreparedStatement

 MySQL Installation on Windows

 MySQL JDBC Driver (MySQL Connector/J)

 MySQL - PreparedStatement

 MySQL - Reference Implementation of JdbcRowSet

 MySQL - JBDC CallableStatement

 MySQL CLOB (Character Large Object) - TEXT

 MySQL BLOB (Binary Large Object) - BLOB

 Oracle Express Edition Installation on Windows

 Oracle JDBC Drivers

 Oracle - Reference Implementation of JdbcRowSet

 Oracle - PreparedStatement

 Oracle - JBDC CallableStatement

 Oracle CLOB (Character Large Object) - TEXT

 Oracle BLOB (Binary Large Object) - BLOB

 Microsoft SQL Server Express Edition

 Microsoft JDBC Driver for SQL Server

 Microsoft JDBC Driver - Query Statements and Result Sets

 Microsoft JDBC Driver - DatabaseMetaData Object

 Microsoft JDBC Driver - DDL Statements

 Microsoft JDBC Driver - DML Statements

 SQL Server - PreparedStatement

 SQL Server CLOB (Character Large Object) - TEXT

 SQL Server BLOB (Binary Large Object) - BLOB

 JDBC-ODBC Bridge Driver - sun.jdbc.odbc.JdbcOdbcDriver

 JDBC-ODBC Bridge Driver - Flat Text Files

 JDBC-ODBC Bridge Driver - MS Access

 JDBC-ODBC Bridge Driver - MS SQL Server

 Summary of JDBC Drivers and Database Servers

 Additional Tutorial Notes to Be Added

 Outdated Tutorials

 References

 Full Version in PDF/EPUB