O Guia Definitivo do Yii 1.1

function having($conditions, $params=array())
The having method specifies the HAVING part of a query. Its usage is the same as where.
Below are some examples:
// HAVING id=1 or id=2
having('id=1 or id=2')
// HAVING id=1 OR id=2
having(array('or', 'id=1', 'id=2'))
union
function union($sql)
The union method specifies the UNION part of a query. It appends $sql to the existing
SQL using UNION operator. Calling union() multiple times will append multiple SQLs to the
existing SQL.
Below are some examples:
// UNION (select * from tbl_profile)
union('select * from tbl_profile')
Executing Queries
After calling the above query builder methods to build a query, we can call the DAO
methods as described in Data Access Objects to execute the query. For example, we can
call CDbCommand::queryRow() to obtain a row of result, or CDbCommand::queryAll() to
get all rows at once. Example:
$users = Yii::app()->db->createCommand()
->select('*')
->from('tbl_user')
->queryAll();
Retrieving SQLs
Besides executing a query built by the Query Builder, we can also retrieve the
corresponding SQL statement. This can be done by calling CDbCommand::getText().