public function set($idSite, $period, $name, $value)
    {
        $row = & $this->get($idSite, $period);
        $row[$name] = $value;
    }
public function set($idSite, $period, $name, $value)
    {
        $row = & $this->get($idSite, $period);
        $row[$name] = $value;
    }
public function set ( $ idSite , $ period , $ name , $ value ) { $ row = & $ this -> get ( $ idSite , $ period ) ; $ row [ $ name ] = $ value ; }
Set data for a specific site & period. If there is no data for the given site ID & period,
it is set to the default row.

@param int $idSite
@param string $period eg, '2012-01-01,2012-01-31'
@param string $name eg 'nb_visits'
@param string $value eg 5
Set data for a specific site & period . If there is no data for the given site ID & period it is set to the default row .