I attempted to reduce your code to something that just set information on a static entry, then printed all the entries. From this, I was able to see that the update worked just fine. So, I'd be inclined to think that the problem might be in the complicated stuff near the end of your code, and not in the actual database update code.

-Scott

#!/usr/bin/perl -w
use strict;
use DBI;
#use autodie;
$\="\n";

my $res_tbl="SOMETABLE";
my $loc_tbl="OTHERTABLE";

my $res_select_stmt = "Select * from $res_tbl order by id";
my $loc_select_stmt = "Select location from $loc_tbl where resource_id
+ = ?";


my $db="SOMEDB";
my $dbun="SOMEUN";
my $dbpw = 'SOMEPW';
my $dbhost="SOMEHOST.hostedresource.com";
my $res_tbl="resource_list";
my $loc_tbl="matrix_locations";

my $drh = DBI->install_driver("mysql") || print "install_driver failed
+: $DBI::errstr <br/>
+";
my $dsn = "DBI:mysql:database=$db;host=$dbhost";
my $dbh = DBI->connect($dsn,$dbun,$dbpw) || print "DB connect failed: 
+$DBI::errstr  <br/>"

my $res_select_stmt = "Select * from $res_tbl order by id";
my $loc_select_stmt = "Select location from $loc_tbl where resource_id
+ = ?";

my $update_res_stmt = "UPDATE $res_tbl SET name=?, link=?, availabilit
+y=? WHERE id=?";

print "Updating $res_tbl item with stuff \n";
my $sth = $dbh->prepare($update_res_stmt) or warn "prepare UPDATE stat
+ement failed:  $dbh->errstr";
my $rv = $sth->execute("test","link test", "test availability", 7) || 
+warn "Execute update failed: $dbh->errstr";
$sth->finish;
print "$res_tbl updated with return value '$rv'.\n";

my $select_sth = $dbh->prepare($res_select_stmt) || print "prepare sta
+tement failed: $DBI::errstr  <br/>";
$select_sth->execute() || print "execute statement failed: $DBI::errst
+r  <br/>";
my $results = $select_sth->fetchall_arrayref();
$select_sth->finish();

foreach my $row (@$results){
    print join ',' , @$row;
    print '\n';
}
$dbh->disconnect();
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