CDbCriteria连接组有错误

Question

I have two table dataset_type and type, now in the type model, I want to create CActiveDataProvider and use CDbCriteria in sql is

 select type.name, type.description , count(dataset_type.dataset_id) as number
 from type ,dataset_type 
 where type.id=dataset_type.type_id 
 group by type.id

How can i write by CDbCriteria

I try to write

$criteria=new CDbCriteria;
$criteria->select='type.name, type.description, count(dataset_type.dataset_id) as number';
$criteria->join='LEFT JOIN dataset_type ON dataset_type.type_id=id';
$criteria->group='type.id';


//$criteria->compare('id',$this->id);
//$criteria->compare('LOWER(name)',strtolower($this->name) , true);
//$criteria->compare('LOWER(description)',strtolower($this->description) , true);

return new CActiveDataProvider($this, array(
    'criteria'=>$criteria,
));

but it shows error

CDbCommand failed to execute the SQL statement: SQLSTATE[42702]: Ambiguous column: 7 ERROR: column reference "id" is ambiguous at character 163. The SQL statement executed was: 

SELECT COUNT(*) 
FROM (SELECT type.name, type.description, count(dataset_type.dataset_id) as number 
FROM "type" "t" 
LEFT JOIN dataset_type ON dataset_type.type_id=id 
GROUP BY type.id) sq

Answer 1

You should use t.id in following line :-
$criteria->join='LEFT JOIN dataset_type ON dataset_type.type_id=t.id';
As t is alias of type table.