Add quickstart docs for Active Record and SqlMap

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+<com:TContent ID="body">
+<!-- $Id $ -->
+
+<h1>Data Mapper</h1>
+<p>Data Mappers moves data between objects and a database while keeping them 
+	independent of each other and the mapper itself. If you started with
+	<a href="?page=Database.ActiveRecord">Active Records</a>, you may eventually
+	 faced with more complex business
+	objects as your project progresses. When you build an object model with a
+	 lot of business logic it's valuable to use these mechanisms to better organize
+	 the data and the behavior that goes with it. Doing so leads to variant schemas;
+	 that is, the object schema and the relational schema don't match up.
+</p>
+
+<p>The Data Mapper separates the in-memory objects from the database. Its responsibility 
+	is to transfer data between the two and also to isolate them from each other. 
+	With Data Mapper the in-memory objects needn't know even that there's a database 
+	present; they need no SQL interface code, and certainly no knowledge of the
+	 database schema. (The database schema is always ignorant of the objects that use it.) 
+</p>
+
+<h2>When to Use It</h2>
+<p>The primary occasion for using Data Mapper is when you want the database schema
+	 and the object model to evolve independently. Data Mapper's primary benefit is
+	 that when working on the business (or domain) objects you can ignore the database, both in
+	 design and in the build and testing process. The domain objects have no idea
+	 what the database structure is, because all the correspondence is done by the mappers.
+</p>
+
+<p>This helps you in the code because you can understand and work with the domain objects 
+	without having to understand how they're stored in the database. You can modify the 
+	business models or the database without having to alter either. With complicated
+	mappings, particularly those involving <b>existing databases</b>, this is very valuable.
+</p>
+
+<p>The price, of course, is the extra layer that you don't get with 
+	<a href="?page=Database.ActiveRecord">Active Record</a>, 
+	so the test for using these patterns is the complexity of the business logic. 
+	If you have fairly simple business logic, an <a href="?page=Database.ActiveRecord">Active Record</a> 
+	will probably work. 
+	For more complicated logic a Data Mapper may be more suitable.
+</p>
+
+<h2>SqlMap Data Mapper</h2>
+<p>The SqlMap DataMapper framework makes it easier to use a database with a PHP application. 
+	SqlMap DataMapper couples objects with stored procedures or SQL statements using 
+	a XML descriptor. Simplicity is the biggest advantage of the SqlMap DataMapper over 
+	object relational mapping tools. To use SqlMap DataMapper you rely on your own objects, 
+	XML, and SQL. There is little to learn that you don't already know. 
+	With SqlMap DataMapper you have the full power of both SQL and stored procedures at
+	your fingertip
+</p>
+
+<p>
+	<img src=<%~ diagram.png %> alt="SqlMap Data Mapper Overview" id="fig:sqlmap.png" class="figure"/>
+	
+	Here's a high level description of the work flow illustrated in the figure abov. 
+	Provide a parameter, either as an object or a primitive type. The parameter can be
+	 used to set runtime values in your SQL statement or stored procedure. If a runtime value 
+	is not needed, the parameter can be omitted.
+</p>
+<p>Execute the mapping by passing the parameter and the name you gave the statement or 
+	procedure in your XML descriptor. This step is where the magic happens. The framework
+	 will prepare the SQL statement or stored procedure, set any runtime values using your 
+	parameter, execute the procedure or statement, and return the result.
+</p>
+
+<p>In the case of an update, the number of rows affected is returned. In the case of a
+	 query, a single object, or a collection of objects is returned. Like the parameter, 
+	the result object, or collection of objects, can be a plain-old object or a primitive PHP type.
+</p>
+
+<h2>Setting up a database connection and initializing the SqlMap</h2>
+<p>
+	A database connection for SqlMap can be set as follows.
+	See <a href="?page=Database.DAO">Establishing Database Connection</a> for
+	futher details regarding creation of database connection in general.
+<com:TTextHighlighter Language="php" CssClass="source">
+//create a connection and give it to the SqlMap manager.
+$dsn = 'pgsql:host=localhost;dbname=test'; //Postgres SQL
+$conn = new TDbConnection($dsn, 'dbuser','dbpass');
+$manager = new TSqlMapManager($conn);
+$manager->configureXml('my-sqlmap.xml');
+$sqlmap = $manager->getSqlMapGateway(); 
+</com:TTextHighlighter>	
+</p>
+
+<p>
+	The <tt>TSqlMapManager</tt> is responsible for setting up the database connection
+	and configuring the SqlMap with given XML file(s). The <tt>configureXml()</tt>
+	method accepts a string that points to a SqlMap XML configuration file. Once
+	configured, call the <tt>getSqlMapGateway()</tt> method to obtain an instance
+	of the SqlMap gateway interface (use this object to insert/delete/find records).
+</p>
+
+<p>
+	SqlMap database connection can also be configured using a <tt>&lt;module&gt;</tt>
+	tag in the <a href="?page=Configurations.AppConfig">application.xml</a> 
+	or <a href="?page=Configurations.PageConfig">config.xml</a> as follows.
+<com:TTextHighlighter Language="xml" CssClass="source">
+<modules>
+  <module id="my-sqlmap" class="System.Data.SqlMap.TSqlMapConfig" 
+        EnableCache="true" ConfigFile="my-sqlmap.xml" >
+    <database ConnectionString="pgsql:host=localhost;dbname=test"
+        Username="dbuser" Password="dbpass" />
+  </module>
+</modules>	
+</com:TTextHighlighter>	
+</p>
+
+<p>
+	The <tt>ConfigFile</tt> attribute should point to a SqlMap configuration file
+	(to be detailed later) either using absolute path, relative path or the 
+	Prado's namespace dot notation path (must omit the ".xml" extension).
+	
+	<div class="tip"><b class="note">Tip:</b>
+		The <tt>EnableCache</tt> attribute when set to "true" will cache the
+		parsed configuration. You must clear or disable the cache if you
+		make chanages your configuration file. 
+		A <a href="?page=Advanced.Performance#6402">cache
+		module</a> must also be defined for the cache to function.
+	</div>	
+</p>
+
+<p>To obtain the SqlMap gateway interface from the &lt;module&gt; configuration, simply
+	do, for example,
+<com:TTextHighlighter Language="php" CssClass="source">
+class MyPage extends TPage
+{
+	public function onLoad($param)
+	{
+		parent::onLoad($param);
+		$sqlmap = $this->Application->Modules['my-sqlmap']->Client;
+		$sqlmap->queryForObject(...); //query for some object
+	}
+}
+</com:TTextHighlighter>
+</p>
+
+<h2>A quick example</h2>
+<p>Let us
+	consider the following "users" table that contains two columns named "username" and "email", 
+	where "username" is also the primary key. 
+<com:TTextHighlighter Language="sql" CssClass="source">
+CREATE TABLE users
+(
+	username VARCHAR( 20 ) NOT NULL ,
+	email VARCHAR( 200 ) ,
+	PRIMARY KEY ( username )
+);
+</com:TTextHighlighter>
+</p>
+<p>Next we define our plain <tt>User</tt> class as follows. Notice that
+	the <tt>User</tt> is very simple.
+<com:TTextHighlighter Language="php" CssClass="source">
+class User
+{
+	public $username;
+	public $email;
+}
+</com:TTextHighlighter>
+</p>
+</p>
+
+<p>Next, we need to define a SqlMap XMl configuration file, lets name
+	the file as <tt>my-sqlmap.xml</tt>
+<com:TTextHighlighter Language="xml" CssClass="source">
+<?xml version="1.0" encoding="utf-8" ?>
+<sqlMapConfig>
+    <select id="SelectUsers" resultClass="User">
+        SELECT username, email FROM users
+    </select>
+</sqlMapConfig>
+</com:TTextHighlighter>
+</p>
+<p>The &lt;select&gt; tag returns defines an SQL statement. The <tt>id</tt>
+	attribute will be used as the identifier for the query. The <tt>resultClass</tt>
+	attribute value is the name of the class the the objects to be returned.
+	We can now query the objects as follows:
+	
+<com:TTextHighlighter Language="php" CssClass="source">
+//assume that $sqlmap is an TSqlMapGateway instance
+$userList = $sqlmap->queryForList("SelectUsers");
+
+//Or just one, if that's all you need:
+$user = $sqlmap->queryForObject("SelectUsers");
+</com:TTextHighlighter>
+</p>
+
+<p>The above example shows demonstrates only a fraction of the capabilities
+	of the SqlMap Data Mapper. Further details can be found in the 
+	<a href="http://www.pradosoft.com/demo/sqlamp/">SqlMap Manual</a>.
+</p>
+
+<h2>Combining SqlMap with Active Records</h2>
+<p>The above example may seem trival and it also seems that there is
+	alot work just to retrieve some data. However, notice that the <tt>User</tt>
+	class is totally unware of been stored in the database, and the database is
+	unware of the <tt>User</tt> class. 
+</p>
+<p>
+	One of advantages of SqlMap is the
+	ability to map complex object relationship, collections from an existing
+	database. On the other hand, <a href="?page=Database.ActiveRecord">Active Record</a> 
+	provide a very simple way
+	to interact with the underlying database but unable to do more complicated
+	relationship or collections. A good compromise is to use SqlMap to retrieve
+	complicated relationships and collections as Active Record objects and then using
+	these Active Records to do the updates, inserts and deletes.
+</p>
+<p>Continuing with the previous example, we change the definition of the
+	<tt>User</tt> class to become an Active Record.
+<com:TTextHighlighter Language="php" CssClass="source">
+class UserRecord extends TActiveRecord
+{
+	public $username; //the column named "username" in the "users" table
+	public $email;
+	
+	private static $_tablename='users'; //table name 
+	
+	/**
+	 * @return TActiveRecord active record finder instance
+	 */
+	public static function finder()
+	{
+		return self::getRecordFinder('UserRecord');
+	}
+}
+</com:TTextHighlighter>
+</p>
+
+<p>We also need to change the definition of the SqlMap XML configuration. We
+	just need to change the value of <tt>resultClass</tt> attribute to <tt>UserRecord</tt>.
+<com:TTextHighlighter Language="xml" CssClass="source">
+<?xml version="1.0" encoding="utf-8" ?>
+<sqlMapConfig>
+    <select id="SelectUsers" resultClass="UserRecord">
+        SELECT username, email FROM users
+    </select>
+</sqlMapConfig>
+</com:TTextHighlighter>
+</p>
+
+
+<p>The PHP code for retrieving the users remains the same, but SqlMap
+	returns Active Records instead, and we can take advantage of the Active Record methods.
+	
+<com:TTextHighlighter Language="php" CssClass="source">
+//assume that $sqlmap is an TSqlMapGateway instance
+$user = $sqlmap->queryForObject("SelectUsers");
+
+$user->email = 'test@example.com'; //change data
+$user->save(); //save it using Active Record
+</com:TTextHighlighter>
+</p>
+
+<h2>References</h2>
+<ul>
+	<li>Fowler et. al. <i>Patterns of Enterprise Application Architecture</i>,
+	Addison Wesley, 2002.</li>
+	<li>xxxx. <i>iBatis Data Mapper</i>, 
+	<a href="http://www.apache.org/ibatis">http://www.apache.org/ibatis</a>.</li>
+</ul>
+
+</com:TContent>
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