JDBC Tutorials - Herong's Tutorial Examples

∟Derby (Java DB) - ResultSet Objects of Queries

∟ResultSet Objects with Update Capability

This section describes how to create ResultSet objects with update capability.

ResultSet objects can also be created with update capability so that they can be used to perform the same functionalities as the "UPDATE", "INSERT" and "DELETE" SQL statements. To create a ResultSet object with update capability, you must follow several guidelines:

• The ResultSet object must be created with a SELECT statement by the executeQury() method on a Statement object.
• The Statement object must be created with ResultSet.CONCUR_UPDATABLE as the concurrency type.
• The SELECT statement must have a single underlying table, with no joins and no aggregations (GROUP BY).
• The underlying table must have a primary key column, which must be selected in result by the SELECT statement.
• All columns that require user values (nonnullable and no default values) in the underlying table must be selected in result by the SELECT statement.
• The JDBC driver must support updatability.

Of course, the Derby JDBC driver does support updatability. So I wrote the following sample program to update one row of the Profile table:

Here is a sample program that updated one row in the Profile table through a ResultSet object:

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

// Create a Statement for scrollable ResultSet
      Statement sta = con.createStatement(
        ResultSet.TYPE_FORWARD_ONLY,
        ResultSet.CONCUR_UPDATABLE);

// Catch the ResultSet object
      ResultSet res = sta.executeQuery(
        "SELECT * FROM Profile WHERE ID = 9");

// Check ResultSet's updatability
      if (res.getConcurrency() == ResultSet.CONCUR_READ_ONLY) {
        System.out.println("ResultSet non-updatable.");
      } else {
        System.out.println("ResultSet updatable.");
      }

// Move the cursor to the first row
      res.next();

// Get the current first name and last name
      String firstName = res.getString("FirstName");
      String lastName = res.getString("LastName");
      System.out.println("Current name: "+firstName+" "+lastName);

// Set the new first name and last name
      res.updateString("FirstName", "Johnny");
      res.updateString("LastName", "Caprio");
      res.updateRow();

// Can not get the updated first name and last name back
//      firstName = res.getString("FirstName");
//      lastName = res.getString("LastName");
//      System.out.println("Updated name: "+firstName+" "+lastName);
      System.out.println("Updated name: Johnny Caprio");

// Close ResultSet and Statement
      res.close();
      sta.close();

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

Here is the output:

ResultSet updatable.
Current name: 11bd 99552
Updated name: Johnny Caprio

Notice that I commented out 3 lines of code, because getXXX() methods give me exceptions when called after the updateRow() method. This is not mentioned in the JDBC API document.

Exception: Invalid operation at current cursor position.

Table of Contents

 About This Book

 JDBC (Java Database Connectivity) Introduction

 JDK (Java SE) Installation

 Installing and Running Derby (Java DB)

 Derby (Java DB) JDBC Driver

 Derby (Java DB) JDBC DataSource Objects

 Derby (Java DB) - DML Statements

►Derby (Java DB) - 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

 Derby (Java DB) - PreparedStatement

 Summary of JDBC Drivers and Database Servers

 Using Connection Pool with JDBC

 Archived Tutorials

 References

 Full Version in PDF/EPUB

ResultSet Objects with Update Capability - Updated in 2024, by Herong Yang