I am trying to build a hash depending on the in a database table that contains a 1 or 0 depending if there is data for a given element.

Given the following input table: 

id    fname    lname
1     Joe      Smith
2     Sally    Smith

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Here is the code I am using: 

use DBI;
$dbh = DBI->connect("DBI:CSV:f_dir=./");
$query = "select id, fname, lname";
$sth->prepare($query);
$sth->execute();
while ($rowdata = $sth->fetchrow_hashref) {
    $hash{$rowdata->{'id'}} = $rowdata{'id'};
    if ($rowdata->{'fname'}) { $hash{$rowdata->{'id'}}{'fname'} = 1; }
    if ($rowdata->{'lname'}) { $hash{$rowdata->{'id'}}{'lname'} = 1; }
}

print Dumper(\%hash);

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Yet, I do not get the expected results. I get the following: 

$VAR1 = {
          '' => undef
        };

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I would expect to see something like the following (constructed my myself and may or may not be valid): 

$VAR1 = {
            {
              '' => 1
              'fname' => 'John'
              'lname' => 'Smith'
            {
            {
              '' => 2
              'fname' => 'Sally'
              'lname' => 'Smith'
            {
        };

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Update: Changed all references to $rowdata{} to $rowdata->{}.

In reply to building a hash from a database by bfdi533

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