Updating an Interbase BLOB field

[rtcary]

I have a table, MyCalls, that has several fields, one of whcih is a blob field. The name of the field is Comments.

I am able to read the data with

$dbh = db_open($host, $user, $password);
if ($dbh) {
  $sthdl = db_get_call_data($dbh, $call_id);
  if ($sthdl) {
    $row = ibase_fetch_object($sthdl);
    if ($row->COMMENTS) {
      $bid = ibase_blob_open($row->COMMENTS);
      if ($bid) {
        $my_comments = ibase_blob_get($bid, 2048);
        ibase_blob_close($bid);
      }
    }
  }
}

Let's say I do $my_omments = $my_comments . "Something new";
Now how would I do an UPDATE query to the COMMENTS field?

Many thanks....

Todd