Table of Contents

Using the 1.5 Database Libraries

Getting a database object

This tutorial should provide you with the basics of what you need to know to use the Joomla! database libraries.

Get the system database object

The easiest way to get a database object is by getting the system database object returned by the JFactory class. The static method JFactory::getDBO() returns a singleton instance of the system database object regardless of scope and is the recommended way of getting this object. 

// This gets the database object using the JFactory class
$db = &JFactory::getDBO();

Creating a custom database object

Joomla! 1.5 introduces the concept of database drivers which will allow you to get database objects that point to different database sources. 

// Create a new database object
$myDB = new JDatabase::getInstance( $options );

Using the database object

For the purposes of this tutorial we will use a very simple database table that stores information about dogs. The database table has a dog_id field with a unique integer id field, a name field and a color field for each dog. To keep things simple we have only added three dogs to our database table:

Dog 1 is named Spot and is white.

Dog 2 is named Fido and is brown.

Dog 3 is named Buster and is also brown.

The following table represents our database table which we will simply call, dogs.

<informaltable> <tgroup cols=”3”> <thead> <row> <entry align=”center”>dog_id</entry> <entry align=”center”>name</entry> <entry align=”center”>color</entry> </row> </thead> <tbody> <row> <entry>1</entry> <entry>Spot</entry> <entry>white</entry> </row> <row> <entry>2</entry> <entry>Fido</entry> <entry>brown</entry> </row> <row> <entry>3</entry> <entry>Buster</entry> <entry>brown</entry> </row> </tbody> </tgroup> </informaltable>

Select one field from one row

Lets say for example that I want to find out the name of the second dog in my database table. This is a fairly straightfoward task, I simply need to get the name value in the name field where the dog_id is 2 so lets build an SQL query to do that. 

SELECT name FROM dogs WHERE dog_id = 2

Easy enough, now we need to actually get the value using our database object.

First we need to get ourselves a database object that is connected to the database our dogs table is in. 

// Get the system database object.
$db = &JFactory::getDBO();

Next we need to set our query to the database object. To do this we will use the setQuery method. 

// Set our query to the database object.
$db->setQuery( 'SELECT name FROM dogs WHERE dog_id = 2' );

Lastly we call the loadResult() method. 

// Use the loadResult() method to get only the first value from the first row of the result set.
$name = $db->loadResult();