The CData ADO.NET Provider for QuickBooks Online implements two ADO.NET interfaces you can use to retrieve data from QuickBooks Online: QuickBooksOnlineDataAdapter and QuickBooksOnlineDataReader objects. Whereas QuickBooksOnlineDataAdapter objects retrieve a single result set of all the data that matches a query, QuickBooksOnlineDataReader objects fetch data in subset increments as needed.

Using the QuickBooksOnlineDataReader

The QuickBooksOnlineDataReader retrieves data faster than the QuickBooksOnlineDataAdapter because it can retrieve data in pages. As you read data from the QuickBooksOnlineDataReader, it periodically requests the next page of results from the data source, if required. This causes results to be returned at a faster rate. The following example selects all the columns from the Customers table:

C#

string connectionString = "InitiateOAuth=GETANDREFRESH;";

using (QuickBooksOnlineConnection connection = new QuickBooksOnlineConnection(connectionString)) {
  QuickBooksOnlineCommand cmd = new QuickBooksOnlineCommand("SELECT * FROM Customers", connection);
  
  QuickBooksOnlineDataReader rdr = cmd.ExecuteReader();

  while (rdr.Read()) {
    Console.WriteLine(String.Format("\t{0} --> \t\t{1}", rdr["Id"], rdr["GivenName"]));
  }
}

VB.NET

Dim connectionString As String = "InitiateOAuth=GETANDREFRESH;"

Using connection As New QuickBooksOnlineConnection(connectionString)
  Dim cmd As New QuickBooksOnlineCommand("SELECT * FROM Customers", connection)

  Dim rdr As QuickBooksOnlineDataReader = cmd.ExecuteReader()

  While rdr.Read()
    Console.WriteLine([String].Format(vbTab & "{0} --> " & vbTab & vbTab & "{1}", rdr("Id"), rdr("GivenName")))
  End While
End Using