#################################################
# Comments:
# This CGI program iniatally displays an HTML
# form with 3 check boxes.  When the user presses
# the SUBMIT button, the program is called again,
# this time the buttons are parsed if any one of
# them were selected.  The corresponding columns
# of a database table are then retrieved and
# displayed inside an HTML table.
#################################################

use strict;
use DBI;
use CGI qw(:standard);

print header;

# you can replace this predicate with code that
# looks for a text box param named 'user'
# once you get the value, you can lookup their
# setting in the appropriate table - I suggest
# just simply saving a comma joined string of
# the column names, such as 'A, B, C' - unless
# you are against breaking the 1st normal rule
if (my @cols = param('cols')) {

   &printForm;

   # substitute your host, user, and password
   my ($host,$user,$pass) = qw(host user pass);

   my $conn = DBI->connect("DBI:mysql:mysql:$host", $user, $pass)
      or print "$0: Can't connect to mysql\n";

   # construct the SQL code to select only those rows user selected
   my $sql = "SELECT " . join(', ', @cols) . " FROM foo.bar";

   my $stmt = $conn->selectall_arrayref($sql)
      or print "Query Failed: ", $conn->errstr, "\n";

   # print table beginning tags and column names row
   print "<table border=1>";
   print "<tr>";
   foreach (@cols) {
      print "<th>$_</th>";
   }
   print "</tr>";
 
   # print the rows of returned data
   foreach my $row (@$stmt) {
      print "<tr>";
      print map {
         $_ = ($_ eq '')
            ? "<td>\&nbsp\;</td>"
            : "<td>$_</td>"
         } @{$row};
      print "</tr>";
   }
   print "</table>";

   $conn->disconnect;
}
else {
   &printForm;
}

sub printForm() {

   print <<_FORM_;
   <HR>
   @{[startform('POST',script_name)]}
   <P>
   Selct Columns:
   @{[checkbox_group(-name=>'cols', -values= ['A','B','C'])]}<P>
   @{[submit('Get Data')]}<P>
   @{[endform]}<P>
   <HR>
_FORM_
}