public function max($colName)
    {
        $max = -INF;
        foreach ($this->rows as $row) {
            if ($max<$row[$colName]) {
                $max = $row[$colName];
            }
        }
        return $max;
    }
public function max($colName)
    {
        $max = -INF;
        foreach ($this->rows as $row) {
            if ($max<$row[$colName]) {
                $max = $row[$colName];
            }
        }
        return $max;
    }
public function max ( $ colName ) { $ max = - INF ; foreach ( $ this -> rows as $ row ) { if ( $ max < $ row [ $ colName ] ) { $ max = $ row [ $ colName ] ; } } return $ max ; }
Return the max of a field

Examples: $maxSale = $dataStore->max("saleAmount");

@param string $colName Name of column you want to get max

@return float Max value of column
Return the max of a field