select SUM in Cake

When I tried using follow code to get the sum of the column named Serviceinfo.services

$conditions = array('fields'=>array('SUM(Serviceinfo.services) a开发者_运维问答s servicecount'),'conditions'=>array('time_id BETWEEN ? AND ?'=>array($startid,$endtid)));
$services = $this->Serviceinfo->find('all',$conditions);

I had to fetch the sum data with services[0][0]['servicecount'] which seems a little weird.And What I expect is services['Serviceinfo']['servicecount'],or more simple one.Then how can I fix this?Thanks in advance!

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Try it as:

'SUM(Serviceinfo.services) as Serviceinfo.servicecount'