himik,

Disclaimer: Have used SQL, but not in a long time. So I'm more interested in the Perl benefits to the solution.

Why not define a string field of 16 characters(128 bits) or whatever and use Perl to encode/decode the 'checkbox' string. if "\0" cannot be supported by you database then this wouldn't work. You can test this by sending a string of '0..255' to the data base and then see if it returns all characters exactly. (Untested).

        my $str = "";
        for ( 0..255 )
        {  $str .= chr($_);  }
[download]

Perl's pack/unpack may be very valuable for this.

Have you ruled out a 128 character string with "Y" or "N" as a possibility? Disk space is pretty cheap today!

Good Luck!