O Guia Definitivo do Yii 1.1

$sql = Yii::app()->db->createCommand()
->select('*')
->from('tbl_user')
->text;
If there are any parameters to be bound to the query, they can be retrieved via the
CDbCommand::params property.
Alternative Syntax for Building Queries
Sometimes, using method chaining to build a query may not be the optimal choice. The Yii
Query Builder allows a query to be built using simple object property assignments. In
particular, for each query builder method, there is a corresponding property that has the
same name. Assigning a value to the property is equivalent to calling the corresponding
method. For example, the following two statements are equivalent, assuming $command
represents a CDbCommand object:
$command->select(array('id', 'username'));
$command->select = array('id', 'username');
Furthermore, the CDbConnection::createCommand() method can take an array as the
parameter. The name-value pairs in the array will be used to initialize the properties of the
created CDbCommand instance. This means, we can use the following code to build a
query:
$row = Yii::app()->db->createCommand(array(
'select' => array('id', 'username'),
'from' => 'tbl_user',
'where' => 'id=:id',
'params' => array(':id'=>1),
))->queryRow();
Building Multiple Queries
A CDbCommand instance can be reused multiple times to build several queries. Before
building a new query, however, the CDbCommand::reset() method must be invoked to
clean up the previous query. For example:
$command = Yii::app()->createCommand();
$users = $command->select('*')->from('tbl_users')->queryAll();
$command->reset(); // clean up the previous query
$posts = $command->select('*')->from('tbl_posts')->queryAll();
Building Data Manipulation Queries