tutorial.html

<?xml version="1.0"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<!-- 
Copyright 2004-2006 H2 Group. Licensed under the H2 License, Version 1.0 (http://h2database.com/html/license.html). 
Initial Developer: H2 Group
-->
<html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en">
<head><meta http-equiv="Content-Type" content="text/html;charset=utf-8" /><title>
Tutorial
</title><link rel="stylesheet" type="text/css" href="stylesheet.css" />
<script type="text/javascript" src="navigation.js"></script>
</head><body onload="frameMe();">
<table class="content"><tr class="content"><td class="content"><div class="contentDiv">

<h1>Tutorial</h1>
<a href="#tutorial_starting_h2_console">
    Starting and Using the H2 Console</a><br />
<a href="#connecting_using_jdbc">
    Connecting to a Database using JDBC</a><br />
<a href="#creating_new_databases">
    Creating New Databases</a><br />
<a href="#using_server">
    Using the Server</a><br />    
<a href="#using_hibernate">
    Using Hibernate</a><br />
<a href="#web_applications">
    Using Databases in Web Applications</a><br />
<a href="#csv">
    CSV (Comma Separated Values) Support</a><br />
<a href="#upgrade_backup_restore">
    Upgrade, Backup, and Restore</a><br />
<a href="#open_office">
    Using OpenOffice Base</a><br />
<a href="#web_start">
    Java Web Start / JNLP</a><br />

<br /><a name="tutorial_starting_h2_console"></a>
<h2>Starting and Using the H2 Console</h2>
<p>
This application lets you access a SQL database using a browser interface.
This can be a H2 database, or another database that supports the JDBC API.
</p>
<img src="images/console.png" alt="Web Browser - H2 Console Server - H2 Database" />
<p>
This is a client / server application, so both a server and a client (a browser) are required to run it.
</p><p>
Depending on your platform and environment, there are multiple ways to start the application:
</p>
<table><tr><th>OS</th><th>Start</th></tr>
<tr>
  <td>Windows</td>
  <td>
    Click [Start], [All Programs], [H2], and [H2 Console (Command Line)]<br />
    When using the Sun JDK 1.4 or 1.5, a window with the title 'H2 Console ' should appear.
    When using the Sun JDK 1.6, an icon will be added to the system tray:
    <img src="images/h2.png" alt="[H2 icon]" /><br />
    If you don't get the window and the system tray icon, 
    then maybe Java is not installed correctly (in this case, try another way to start the application).
    A browser window should open and point to the Login page http://localhost:8082).
  </td>
</tr>
<tr>
  <td>Windows</td>
  <td>
    Open a file browser, navigate to h2/bin, and double click on h2.bat.<br />
    A console window appears. If there is a problem, you will see an error message 
    in this window. A browser window will open and point to the Login page 
    (URL: http://localhost:8082).
  </td>
</tr>
<tr>
  <td>Any</td>
  <td>
      Open a console window, navigate to the directory 'h2/bin' and type:
<pre>
java -cp h2.jar org.h2.tools.Server
</pre>
  </td>
</tr>
</table>

<h3>Firewall</h3>
<p>
If you start the server, you may get a security warning from the firewall (if you have installed one).
If you don't want other computers in the network to access the application on your machine, you can
let the firewall block those connections. The connection from the local machine will still work.
Only if you want other computers to access the database on this computer, you need allow remote connections
in the firewall.
</p><p>
A small firewall is already built into the server: other computers may not connect to the server by default. 
To change this, go to 'Preferences' and select 'Allow connections from other computers'.
</p>

<h3>Native Version</h3>
The native version does not require Java, because it is compiled using GCJ.
However H2 does currently not run stable with GCJ on Windows
It is possible to compile the software to different platforms. 

<h3>Testing Java</h3>
To check the Java version you have installed, open a command prompt and type:
<pre>
java -version
</pre>
If you get an error message, you may need to add the Java binary directory to the path environment variable.

<h3>Error Message 'Port is in use'</h3>
You can only start one instance of the H2 Console, 
otherwise you will get the following error message:
<code>Port is in use, maybe another ... server already running on...</code>.
It is possible to start multiple console applications on the same computer (using different ports),
but this is usually not required as the console supports multiple concurrent connections.

<h3>Using another Port</h3>
If the port is in use by another application, you may want to start the H2 Console on a different port.
This can be done by changing the port in the file .h2.server.properties. This file is stored
in the user directory (for Windows, this is usually in "Documents and Settings/&lt;username&gt;").
The relevant entry is webPort.

<h3>Starting Successfully</h3>
If starting the server from a console window was successful, 
a new window will open and display the following text:
<pre>
H2 Server running on port 9092
Webserver running on https://localhost:8082/
</pre>
Don't click inside this window; otherwise you might block the application (if you have the Fast-Edit mode enabled).

<h3>Connecting to the Server using a Browser</h3>
If the server started successfully, you can connect to it using a web browser.
The browser needs to support JavaScript, frames and cascading stylesheets (css).
If you started the server on the same computer as the browser, go to http://localhost:8082 in the browser.
If you want to connect to the application from another computer, you need to provide the IP address of the server, for example:
http://192.168.0.2:8082. If you enabled SSL on the server side, the URL needs to start with HTTPS.

<h3>Multiple Concurrent Sessions</h3>
Multiple concurrent browser sessions are supported. As that the database objects reside on the server,
the amount of concurrent work is limited by the memory available to the server application.

<h3>Application Properties</h3>
Starting the server will create a configuration file in you local home directory called <code>.h2.server.properties</code>.
For Windows installations, this file will be in the directory <code>C:\Documents and Settings\[username]</code>.
This file contains the settings of the application.

<h3>Login</h3>
<p>
At the login page, you need to provide connection information to connect to a database.
Set the JDBC driver class of your database, the JDBC URL, user name and password.
If you are done, click [Connect].
</p><p>
You can save and reuse previously saved settings. The settings are stored in the 
Application Properties file.
</p>

<h3>Error Messages</h3>
Error messages in are shown in red. You can show/hide the stack trace of the exception
by clicking on the message.

<h3>Adding Database Drivers</h3>
<p>
Additional database drivers can be registered by adding the Jar file location of the driver to the environment
variables H2DRIVERS or CLASSPATH. Example (Windows): To add the database driver library 
C:\Programs\hsqldb\lib\hsqldb.jar, set the environment variable H2DRIVERS to 
C:\Programs\hsqldb\lib\hsqldb.jar.
</p><p>
Multiple drivers can be set; each entry needs to be separated with a ';' (Windows) or ':' (other operating systems).
Spaces in the path names are supported. The settings must not be quoted.
</p><p>
Only the Java version supports additional drivers (this feature is not supported by the Native version).
</p>

<h3>Using the Application</h3>
The application has three main panels, the toolbar on top, the tree on the left and the query / result panel on the right.
The database objects (for example, tables) are listed on the left panel.
Type in a SQL command on the query panel and click 'Run'. The result of the command appears just below the command.

<h3>Inserting Table Names or Column Names</h3>
The table name and column names can be inserted in the script by clicking them in the tree.
If you click on a table while the query is empty, a 'SELECT * FROM ...' is added as well.
While typing a query, the table that was used is automatically expanded in the tree.
For, example if you type 'SELECT * FROM TEST T WHERE T.' then the table TEST is automatically expanded in the tree.

<h3>Disconnecting and Stopping the Application</h3>
<p>
On the browser, click 'Disconnect' on the toolbar panel. You will be logged out of the database.
However, the server is still running and ready to accept new sessions.
</p><p>
To stop the server, right click on the system tray icon and select [Exit]. 
If you don't have the icon (because you started it in another way), 
press [Ctrl]+[C] on the console where the server was started (Windows),
or close the console window.
</p>

<br /><a name="connecting_using_jdbc"></a>
<h2>Connecting to a Database using JDBC</h2>
To connect to a database, a Java application first needs to load the database driver, 
and then get a connection. A simple way to do that is using the following code:
<pre>
import java.sql.*;
public class Test {
  public static void main(String[] a) 
  throws Exception {
    Class.forName("org.h2.Driver");
    Connection conn = DriverManager.
      getConnection("jdbc:h2:~/test", "sa", ""); 
    // add application code here
  }
}
</pre>
This code first loads the driver (<code>Class.forName()</code>)
and then opens a connection (using <code>DriverManager.getConnection()</code>).
The driver name is <code>"org.h2.Driver"</code> in every case.
The database URL always needs to start with <code>jdbc:h2:</code>
to be recognized by this database. The second parameter in the <code>getConnection()</code> call
is the user name ('sa' for System Administrator in this example). The third parameter is the password.
Please note that in this database, user names are not case sensitive, but passwords are case sensitive.

<br /><a name="creating_new_databases"></a>
<h2>Creating New Databases</h2>
By default, if the database specified in the URL does not yet exist, a new (empty) 
database is created automatically. The user that created the database automatically becomes
the administrator of this database.

<br /><a name="using_server"></a>
<h2>Using the Server</h2>
H2 currently supports three servers: a Web Server, a TCP Server and an ODBC Server.
The servers can be started in different ways.

<h3>Starting the Server from Command Line</h3>
To start the Server from the command line with the default settings, run
<pre>
java org.h2.tools.Server
</pre>
This will start the Server with the default options. To get the list of options, run
<pre>
java org.h2.tools.Server -?
</pre>
There are options available to use a different ports, and start or not start 
parts of the Server and so on. For details, see the API documentation of the Server tool.

<h3>Connecting to the TCP Server</h3>
To remotly connect to a database using the TCP server, use the following driver and database URL:
<ul>
<li>JDBC driver class: org.h2.Driver
</li><li>Database URL: jdbc:h2:tcp://localhost/~/test
</li></ul>
For details about the database URL, see also in Features.

<h3>Starting the Server within an Application</h3>
It is also possible to start and stop a Server from within an application. Sample code:
<pre>
import org.h2.tools.Server;
...
// start the TCP Server
Server server = Server.createTcpServer(args).start();
...
// stop the TCP Server
server.stop();
</pre>

<h3>Stopping a TCP Server from Another Process</h3>
The TCP Server can be stopped from another process. 
To stop the server from the command line, run:
<pre>
java org.h2.tools.Server -tcpShutdown tcp://localhost:9092
</pre>
To stop the server from a user application, use the following code:
<pre>
org.h2.tools.Server.shutdownTcpServer("tcp://localhost:9094");
</pre>
This function will call System.exit on the server.
This function should be called after all connection to the databases are closed 
to avoid recovery when the databases are opened the next time.
To stop remote server, remote connections must be enabled on the server.

<h3>Limitations of the Server</h3>
There currently are a few limitations when using the server or cluster mode:
<ul>
<li>Statement.cancel() is only supported in embedded mode.
    A connection can only execute one operation at a time in server or cluster mode,
    and is blocked until this operation is finished.
</li><li>CLOBs and BLOBs are sent to the server in one piece and not as a stream.
    That means those objects need to fit in memory when using the server or cluster mode.
</li></ul>

<br /><a name="using_hibernate"></a>
<h2>Using Hibernate</h2>
This database supports Hibernate version 3.1 and newer. You can use the HSQLDB Dialect, 
or the native H2 Dialect that is available in the file src/tools/org/h2/tools/hibernate/H2Dialect.txt.
The H2 dialect is included in newer version of Hibernate. For versions where the dialect is missing, you need to copy the file
into the folder src\org\hibernate\dialect (Hibernate 3.1), rename it to H2Dialect.java and re-compile hibernate.

<br /><a name="web_applications"></a>
<h2>Using Databases in Web Applications</h2>
There are multiple ways to access a database from within web
applications. Here are some examples if you use Tomcat or JBoss.

<h3>Embedded Mode</h3>
The (currently) most simple solution is to use the database in the
embedded mode, that means open a connection in your application when
it starts (a good solution is using a Servlet Listener, see below), or
when a session starts. A database can be accessed from multiple
sessions and applications at the same time, as long as they run in the
same process. Most Servlet Containers (for example Tomcat) are just
using one process, so this is not a problem (unless you run Tomcat in
clustered mode). Tomcat uses multiple threads and multiple
classloaders. If multiple applications access the same database at the
same time, you need to put the database jar in the shared/lib or
server/lib directory. It is a good idea to open the database when the
web application starts, and close it when the web applications stops.
If using multiple applications, only one (any) of them needs to do
that. In the application, an idea is to use one connection per
Session, or even one connection per request (action). Those
connections should be closed after use if possible (but it's not that
bad if they don't get closed).

<h3>Server Mode</h3>
The server mode is similar, but it allows you to run the server in another process. 

<h3>Using a Servlet Listener to Start and Stop a Database</h3>
Add the h2.jar file your web application, and
add the following snippet to your web.xml file (after context-param and before filter):
<pre>
&lt;listener>
   &lt;listener-class>org.h2.server.web.DbStarter&lt;/listener-class>
&lt;/listener>
</pre>

For details on how to access the database, see the code DbStarter.java

<br /><a name="csv"></a>
<h2>CSV (Comma Separated Values) Support</h2>
The CSV file support can be used inside the database using the functions CSVREAD and CSVWRITE, 
and the CSV library can be used outside the database as a standalone tool.

<h3>Writing a CSV File from Within a Database</h3>
The built-in function CSVWRITE can be used to create a CSV file from a query.
Example:
<pre>
CREATE TABLE TEST(ID INT, NAME VARCHAR);
INSERT INTO TEST VALUES(1, 'Hello'), (2, 'World');
CALL CSVWRITE('test.csv', 'SELECT * FROM TEST');
</pre>

<h3>Reading a CSV File from Within a Database</h3>
A CSV file can be read using the function CSVREAD. Example:
<pre>
SELECT * FROM CSVREAD('test.csv');
</pre>

<h3>Writing a CSV File from a Java Application</h3>
The CSV tool can be used in a Java application even when not using a database at all.
Example:
<pre>
SimpleResultSet rs = new SimpleResultSet();
rs.addColumn("NAME", Types.VARCHAR, 255, 0);
rs.addColumn("EMAIL", Types.VARCHAR, 255, 0);
rs.addColumn("PHONE", Types.VARCHAR, 255, 0);
rs.addRow(new String[]{"Bob Meier", "bob.meier@abcde.abc", "+41123456789"});
rs.addRow(new String[]{"John Jones", "john.jones@abcde.abc", "+41976543210"});
Csv.write("test.csv", rs, null);
</pre>

<h3>Reading a CSV File from a Java Application</h3>
It is possible to read a CSV file without opening a database.
Example:
<pre>
ResultSet rs = Csv.read("test.csv", null, null);
ResultSetMetaData meta = rs.getMetaData();
while(rs.next()) {
    for(int i=0; i&lt;meta.getColumnCount(); i++) {
        System.out.println(meta.getColumnLabel(i+1) + ": " + rs.getString(i+1));
    }
    System.out.println();
}
rs.close();
</pre>

<br /><a name="upgrade_backup_restore"></a>
<h2>Upgrade, Backup, and Restore</h2>

<h3>Database Upgrade</h3>
The recommended way to upgrade from one version of the database engine to the next
version is to create a backup of the database (in the form of a SQL script) using the old engine,
and then execute the SQL script using the new engine.

<h3>Backup using the Script Tool</h3>
There are different ways to backup a database. For example, it is possible to copy the database files.
However, this is not recommended while the database is in use. Also, the database files are not human readable
and quite large. The recommended way to backup a database is to create a compressed SQL script file. 
This can be done using the Script tool:
<pre>
java org.h2.tools.Script -url jdbc:h2:~/test -user sa -script test.zip -options compression zip
</pre>
It is also possible to use the SQL command SCRIPT to create the backup of the database.
For more information about the options, see the SQL command SCRIPT.
The backup can be done remotely, however the file will be created on the server side.
The built in FTP server could be used to retrieve the file from the server.

<h3>Restore from a Script</h3>
To restore a database from a SQL script file, you can use the RunScript tool:
<pre>
java org.h2.tools.RunScript -url jdbc:h2:~/test -user sa -script test.zip -options compression zip
</pre>
For more information about the options, see the SQL command RUNSCRIPT.
The restore can be done remotely, however the file needs to be on the server side.
The built in FTP server could be used to copy the file to the server.
It is also possible to use the SQL command RUNSCRIPT to execute a SQL script.
SQL script files may contain references to other script files, in the form of
RUNSCRIPT commands. However, when using the server mode, the references script files
need to be available on the server side.

<h3>Online Backup</h3>
The BACKUP SQL statement and the Backup tool both create a zip file 
with all database files. However, the contents of this file are not human readable. 
Other than the SCRIPT statement, the BACKUP statement does not lock the
database objects, and therefore does not block other users. The resulting
backup is transactionally consistent:
<pre>
BACKUP TO 'backup.zip'
</pre>
The Backup tool (org.h2.tools.Backup) can not be used to create a online backup;
the database must not be in use while running this program.


<br /><a name="open_office"></a>
<h2>Using OpenOffice Base</h2>
OpenOffice.org Base supports database access over the JDBC API. To connect to a H2 database 
using OpenOffice Base, you first need to add the JDBC driver to OpenOffice.
The steps to connect to a H2 database are:
<ul>
<li>Stop OpenOffice, including the autostart
</li><li>Copy h2.jar into the directory &lt;OpenOffice&gt;\program\classes
</li><li>Start OpenOffice Base
</li><li>Connect to an existing database, select JDBC, [Next]
</li><li>Example datasource URL: jdbc:h2:c:/temp/test
</li><li>JDBC driver class: org.h2.Driver
</li></ul>
Now you can access the database stored in the directory C:/temp.


<br /><a name="web_start"></a>
<h2>Java Web Start / JNLP</h2>

When using Java Web Start / JNLP (Java Network Launch Protocol), permissions tags must be set in the .jnlp file, 
and the application .jar file must be signed. Otherwise, when trying to write to the file system, the following 
exception will occur: java.security.AccessControlException: access denied (java.io.FilePermission ... read).

Example permission tags:
<pre>
&lt;security>
    &lt;all-permissions/>
&lt;/security>
</pre>

</div></td></tr></table></body></html>