ADO.NET Provider for Quandl

Build 20.0.7587

Querying with the DataReader

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

Using the QuandlDataReader

The QuandlDataReader retrieves data faster than the QuandlDataAdapter because it can retrieve data in pages. As you read data from the QuandlDataReader, 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 AAPL table:


string connectionString = "ApiKey=abc123;DatabaseCode=WIKI;";

using (QuandlConnection connection = new QuandlConnection(connectionString)) {
  QuandlCommand cmd = new QuandlCommand("SELECT * FROM AAPL", connection);
  QuandlDataReader rdr = cmd.ExecuteReader();

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


Dim connectionString As String = "ApiKey=abc123;DatabaseCode=WIKI;"

Using connection As New QuandlConnection(connectionString)
  Dim cmd As New QuandlCommand("SELECT * FROM AAPL", connection)

  Dim rdr As QuandlDataReader = cmd.ExecuteReader()

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

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Build 20.0.7587