CBaseActiveRelation

public function __construct($name,$className,$foreignKey,$options=array())
{
    $this->name=$name;
    $this->className=$className;
    $this->foreignKey=$foreignKey;
    foreach($options as $name=>$value)
        $this->$name=$value;
}

public function mergeWith($criteria,$fromScope=false)
{
    if($criteria instanceof CDbCriteria)
        $criteria=$criteria->toArray();
    if(isset($criteria['select']) && $this->select!==$criteria['select'])
    {
        if($this->select==='*'||$this->select===false)
            $this->select=$criteria['select'];
        elseif($criteria['select']===false)
            $this->select=false;
        elseif($criteria['select']!=='*')
        {
            $select1=is_string($this->select)?preg_split('/\s*,\s*/',trim($this->select),-1,PREG_SPLIT_NO_EMPTY):$this->select;
            $select2=is_string($criteria['select'])?preg_split('/\s*,\s*/',trim($criteria['select']),-1,PREG_SPLIT_NO_EMPTY):$criteria['select'];
            $this->select=array_merge($select1,array_diff($select2,$select1));
        }
    }

    if(isset($criteria['condition']) && $this->condition!==$criteria['condition'])
    {
        if($this->condition==='')
            $this->condition=$criteria['condition'];
        elseif($criteria['condition']!=='')
            $this->condition="({$this->condition}) AND ({$criteria['condition']})";
    }

    if(isset($criteria['params']) && $this->params!==$criteria['params'])
        $this->params=array_merge($this->params,$criteria['params']);

    if(isset($criteria['order']) && $this->order!==$criteria['order'])
    {
        if($this->order==='')
            $this->order=$criteria['order'];
        elseif($criteria['order']!=='')
            $this->order=$criteria['order'].', '.$this->order;
    }

    if(isset($criteria['group']) && $this->group!==$criteria['group'])
    {
        if($this->group==='')
            $this->group=$criteria['group'];
        elseif($criteria['group']!=='')
            $this->group.=', '.$criteria['group'];
    }

    if(isset($criteria['join']) && $this->join!==$criteria['join'])
    {
        if($this->join==='')
            $this->join=$criteria['join'];
        elseif($criteria['join']!=='')
            $this->join.=' '.$criteria['join'];
    }

    if(isset($criteria['having']) && $this->having!==$criteria['having'])
    {
        if($this->having==='')
            $this->having=$criteria['having'];
        elseif($criteria['having']!=='')
            $this->having="({$this->having}) AND ({$criteria['having']})";
    }
}