my $parameter_value = "option2"; # Your default value from the DB
my $parameter_select = qq(
  <select name="parameter">
    <option value="option1">Option 1
    <option value="option2">Option 2
  </select>
); # your select statement string

if ($parameter_value) {
  $parameter_select =~ s/value="$paremeter_value"/value="$paremeter_value" selected/;
}