Doctrine_RawSql provides convient interface for building raw sql queries. Similar to Doctrine_Query, Doctrine_RawSql provides means for fetching arrays and objects, the way you prefer.
Using raw sql for fetching might be useful when you want to utilize database specific features such as query hints or the CONNECT keyword in Oracle.
Creating Doctrine_RawSql object is easy:
<code type='php'>
$q = new Doctrine_RawSql();
</code>
Optionally a connection parameter can be given:
<code type='php'>
$q = new Doctrine_RawSql($conn); // here $conn is an instance of Doctrine_Connection
The first thing to notice when using Doctrine_RawSql is that you always have to place the fields you are selecting in curly brackets {}. Also for every selected component you have to call addComponent().
The following example should clarify the usage of these:
<code type='php'>
$q = new Doctrine_RawSql();
$q->select('{u.*}')
->from('user')
->addComponent('user', 'User'); // here we tell that user table is bound to class called 'User'
When fetching from multiple components the addComponent calls become a bit more complicated as not only do we have to tell which tables are bound to which components, we also have to tell the parser which components belongs to which.