There are many ways of addressing this issue. The following is not the best, but it works. I have a form where teachers can enter lesson plans and a series of check boxes represent the appropriate grade levels, K through 12. The checkboxes are named GradeK, Grade1, ... Grade12.

When this data is sent via CGI, the parameter is sent to the script as GradeK=on (or whatever value you set the checkbox at). No checkbox parameter is sent if it's not checked. Therefore, I use the following sub to pull the data:

sub getGrades {
    my $grades;
    my @keys = $template->param;

    # Look for the grade parameters and add each one to $grades
    foreach (@keys) {
        $grades .= $1 . ',' if /^Grade([1-9]|1[0-2]|K)$/;
    }
    $grades =~ s/,$//; # remove trailing comma
    return $grades;
}
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This sub is called from the following sub which uses DBI to write the data to a MySQL database:

sub storeData {
    my $table = shift;

    my $grades    = getGrades();
    my $standards = getStandards();

    use DBI;
    my $dbh = DBI->connect("DBI:mysql:$database",$user,$password);
    $dbh->{RaiseError} = 1;

    # save template information to database

    my $sql = 'INSERT INTO ' . $table . '(title,  lesson_summary,
                                              grades, standards) 
                                    VALUES (?, ?, ?, ?)';
    my $sth = $dbh->prepare($sql);

    $sth->execute(
      $template->param('Title'), 
      $template->param('Summary'),
      $grades, 
      $standards
    );
    
    $template->end_html;
    $sth->finish;
    $dbh->disconnect;

    print $template->redirect('http://www.someserver.com/some/path/tha
+nks.html');
}
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This should give you a good start on how to approach this (Grades is defined as varchar(28), by the way).

Cheers,
Ovid