use strict;
use warnings;
use Tk;

my $sql = "";

my $mw     = new MainWindow;
my $top    = $mw->Frame()->pack(-expand  => 1, -fill => "both");
my $f1     = $top->Frame()->pack(-expand => 1, -fill => "x");
my $f2     = $top->Frame()->pack(-expand => 1, -fill => "both");
$f1->Label(-text => "SQL Statement")->pack(-side => "left");
$f1->Entry(-textvar => \$sql, -width => 64)->pack(-side => "left");
$f1->Button(-text => "SQL", -command => \&submit)->pack(-side => "right");
my $output = $mw->Text()->pack(-expand => 1, -fill => "both");
MainLoop();

sub submit {
    # Here, insert the code for submitting the query using $sql...
    my $results = ...

    $output->insert("end", $results);
    $output->see("end");
    $mw->update();

##</code><code>##

TIED INTERFACE

The Perl/Tk Text widget also has built-in TIEHANDLE methods for print
and printf statements. This means you can print to file handles tied
to a Text widget, and the tied methods automatically insert the print
statement's arguments into the Text widget.

For example:

 #!/usr/local/bin/perl -w
 use POSIX 'acos';
 use Tk;
 use strict;

 my $mw = MainWindow->new;
 my $text = $mw->Text(qw/-width 40 -height 10/)->pack;

 tie *STDOUT, ref $text, $text;

 print "Hello Text World!\n";
 printf "pi ~= %1.5f", acos(-1.0);

 MainLoop;