J1.5 talk:Developing a MVC Component/Using the Database

Although it is mentioned in the article, I think it is important to underline where the install.sql and uninstall.sql files have to be placed:

install.sql and uninstall.sql files have to be mentioned in two places:

• In one of the file sections. For example:

  <files folder="admin">
     <filename>...</filename>
     <filename>...</filename>
     <filename>install.sql</filename>
     <filename>uninstall.sql</filename>
  </files>  

• In the install / uninstall sections.

Of course, the files have to be copied in the correct folder (in the example, it should be the admin folder).

When data is read from a database, it can be retrieved in the class constructor:

  // The constructor accesses the database, and retrieves all properties.
  function __construct($config = array()) {
     parent::__construct($config);           // To transmit configuration to parent class.
     $db =& JFactory::getDBO();		
     $query = 'SELECT greeting FROM #__hello';
     $db->setQuery( $query );
     $this->greeting = $db->loadResult();
  }
  // The private property
  var $greeting;
  // The public property accessor
  function getGreeting() {
     return $this->greeting;
  }