Editing Data
We have explained how use ADO to connect to a data source, execute a command, get the results in a Recordset object, and navigate within the Recordset. This section focuses on the next fundamental ADO operation: editing data.
This section continues to use the sample Recordset introduced in Examining Data, with one important change. The following code is used to open the Recordset:
'BeginEditIntro
Dim strSQL As String
Dim objRs1 As ADODB.Recordset
strSQL = "SELECT * FROM Shippers"
Set objRs1 = New ADODB.Recordset
objRs1.Open strSQL, GetNewConnection, adOpenStatic, _
adLockBatchOptimistic, adCmdText
' Disconnect the Recordset from the Connection object.
Set objRs1.ActiveConnection = Nothing
'EndEditIntro
The important change to the code involves setting the CursorLocation property of the Connection object equal to adUseClient in the GetNewConnection function (shown in the next example), which indicates the use of a client cursor. For more information about the differences between client-side and server-side cursors, see Understanding Cursors and Locks.
The CursorLocation property's adUseClient setting moves the location of the cursor from the data source (the SQL Server, in this case) to the location of the client code (the desktop workstation). This setting forces ADO to invoke the Client Cursor Engine for OLE DB on the client in order to create and manage the cursor.
You might also have noticed that the LockType parameter of the Open method changed to adLockBatchOptimistic. This opens the cursor in batch mode. (The provider caches multiple changes and writes them to the underlying data source only when you call the UpdateBatch method.) Changes that were made to the Recordset will not be updated in the database until the UpdateBatch method is called.
Finally, the code in this section uses a modified version of the GetNewConnection function. This version of the function now returns a client-side cursor. The function looks like this:
'BeginNewConnection
Public Function GetNewConnection() As ADODB.Connection
On Error GoTo ErrHandler:
Dim objConn As New ADODB.Connection
Dim strConnStr As String
strConnStr = "Provider='SQLOLEDB';Initial Catalog='Northwind';" & _
"Data Source='MySqlServer';Integrated Security='SSPI';"
objConn.ConnectionString = strConnStr
objConn.CursorLocation = adUseClient
objConn.Open
Set GetNewConnection = objConn
Exit Function
ErrHandler:
Set objConn = Nothing
Set GetNewConnection = Nothing
If Err <> 0 Then
MsgBox Err.Source & "-->" & Err.Description, , "Error"
End If
End Function
'EndNewConnection
This section contains the following topics.
