Fetching Data Asynchronously and progress bar

This is a two part question but related:

1. WHat is the difference between fetching data asynchronously as opposed to synchronously.

2. Which brings me to this question: I bought a code snippet on using a progress bar for two things: one to show how long it takes the records to be brought back from the database, adn the other is processing those records.. this is what I came up with.

Private WithEvents cnnSQL As ADODB.Connection
Private WithEvents rs As ADODB.Recordset

Private Sub Command1_Click()
   Dim maxrecords As Long
   
   Set cnnSQL = New ADODB.Connection
   Set rs = New ADODB.Recordset
   mydsn = "DSN=ARSystem3;uid=myid;pwd=mypwd"
   cnnSQL.Open mydsn
   
   rs.Open "data_count_sel(965520000, 966124799)", cnnSQL
   maxrecords = rs("recordcount")
   rs.Close
   
   ProgressBar1.Max = maxrecords
   
   
   rs.CursorLocation = adUseClient
   rs.Open "data_sel(965520000, 966124799)", cnnSQL, adOpenStatic, adLockReadOnly, adAsyncFetch
   Do While rs.State <> adStateOpen
       DoEvents
   Loop
   ProgressBar1.Value = 0
   Dim i As Long
   i = 0
   Do Until rs.EOF
   i = i + 1
   ProgressBar1.Value = i
   rs.MoveNext
   
   Loop
   
   
   rs.Close
   cnnSQL.Close
   Set rs = Nothing
   Set cnnSQL = Nothing
End Sub

Private Sub Command2_Click()
   rs.Cancel
End Sub

Private Sub rs_FetchProgress(ByVal Progress As Long, ByVal MaxProgress As Long, adStatus As ADODB.EventStatusEnum, ByVal pRecordset As ADODB.Recordset)
   ProgressBar1.Value = Progress
   
   
   'lblprogress.Caption = "Records Fetched: " & Progress & " / " & MaxProgress
End Sub


The progress bar works for both .. I just want to make sure that this is the most efficient way of processing this code. I don't wnat to just copy the work, i want to learn it.. Here are some code snippets I would like to understand what is happening..

'WHat I think is happening is it is the point in time
'where the data is being fetched, up until the recordset
'is actually populated..

Do While rs.State <> adStateOpen
       DoEvents
Loop


How and where does this get called. And what other things could this be used for...
Private Sub rs_FetchProgress(ByVal Progress As Long, ByVal MaxProgress As Long, adStatus As ADODB.EventStatusEnum, ByVal pRecordset As ADODB.Recordset)
   ProgressBar1.Value = Progress
   
   
   'lblprogress.Caption = "Records Fetched: " & Progress & " / " & MaxProgress
End Sub

I think this is a fairly easy question, but because of the length of it, I will post as moderate..


thanks for the help