my $rows = $GetAssignmentID_sth->rows;
  if($rows > 0) {
    while (my ($AssignmentID, $UserCount) = $GetAssignmentID_sth-> fet
+chrow_array() )  {
          push(@AssignmentIDs, $AssignmentID);
    }
  }
[download]

How about completely getting rid of the whole $rows part? It seems redundant (all it does is protect a while loop, that would not be executed anyway if there is no data to loop over), and error-prone ($sth->rows is not guaranteed to be the correct number of rows until you have fetched them all).

while (my ($AssignmentID, $UserCount) = $GetAssignmentID_sth-> fetchro
+w_array() )  {
     push(@AssignmentIDs, $AssignmentID);
}
[download]