Instead of

$new_monthly_page_hits{$page}=@row;
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I think you want to do

$new_monthly_page_hits{$page} = $row[0];
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to actually store the number you got back.

But why do so much work in Perl when you can have the DB do the work?

select page,count(page) 
from counter_monthly
group by page
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will return you a list of pairs (page, hitcount). If you only want a very small subset of the whole database as not all pages are of interest to you, then your approach might be faster though.

You've already received some good advice about the question you originally asked, but here are a few more pointers:

• Inside your foreach loop you are creating a new database handle. This is very inefficient and should be avoided. You want to create a database handle once for an average script and reuse it, rather than paying the connection overhead multiple times. Also, some databases have rather low limits on how many connections can be opened concurrently.
• You received a recommendation about having SQL do the work -- I would definitely take that advice. In cases where you need to step through a list of values, reusing those values in a query, you'll want to read the DBI documentation until you understand how to prepare a statement handle and use the '?' placeholders (to avoid the overhead of recompiling your SQL statement a large number of times).
• I suspect you are still not writing 'use strict;' and 'use warnings;' at the top of your scripts. Whenever you post a code sample, you'll do well to show that you are doing this, if only to avoid people like me saying, "You really should 'use strict' and 'use warnings'! :)

Good luck!

It's times like this that I wish I could ++ a post more than once.

---
It's all fine and dandy until someone has to look at the code.

A couple of quick observations:

1. In the line print "while loop the row for $page is @row\n";, you should escape @row (ie. \@row), since it will otherwise try to interpolate the values of @row into the string.
2. In the next line $new_monthly_page_hits{$page}=@row; you are assigning to the array @row in scalar context, which means you're taking the number of items in @row, NOT the actual values from the array.  Since the value you actually want to assign to is probably the first element in the array, try assigning to $row[0] instead (or use Data::Dumper to print out the contents of @row, so you can see what's going on).

I hope that provides you some help.

I have a hash and the keys are page names.

(snip)

I want to create another hash using the page names as the keys and the count() result as the values.

my %orig= # ...
my %new;
$new{$_}=however_you_get_it_from($_) for keys %orig;
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or

my %new=map { $_ => however_you_get_it_from($_) } keys %orig;
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or...

# %yearly_page_hits defined elsewhere

my %new_monthly_page_hits;

# do this outside of the loop
my $dbh = DBI->connect("DBI:mysql:$sqlDatabaseName:","$mysqlUsername",
+"$mysqlPassword")
    or die "Connection Error: $DBI::errstr\n";

# loop through page keys
foreach my $page (keys %yearly_page_hits) {
    # a single DBI call does it all
    if (my @row = $dbh->selectrow_array(
        "select count(page) from counter_monthly where page='$page'"))
+ {
        $new_monthly_page_hits{$page} = $row[0];
    }
    else {
        $new_monthly_page_hits{$page} = 0;
    }
    print "$page $new_monthly_page_hits{$page}<br><br>";
}
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