my $sql = qq! SELECT 
                 a."FirstName"::TEXT || ' ' ||a."LastName" AS "Labels",  
                 ROUND(SUM((b."UnitPrice" - b."Discount") * b."Quantity")) AS "Data"  
              FROM "Employees" a, "Order_Details" b, "Orders" c  
              WHERE a."EmployeeID" = c."EmployeeID" AND  
                    b."OrderID" = c."OrderID"  
              GROUP BY 1  
              ORDER BY 2 DESC  
              LIMIT 10!; 
my $sth=$dbh->prepare("$sql"); 
$sth->execute() || quit(); 
while (my $ref = $sth->fetchrow_hashref()) { 
 
my $labels  = $ref->{'Labels'}; 
my $data    = $ref->{'Data'}; 
} 

##</code><code>##

$labels = [label1, label2, label3.....];
$data   = [data1, data2, data3.........];