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

Using the HarperDBDataAdapter

Use the adapter's Fill method to retrieve data from the data source. An empty DataTable instance is passed as an argument to the Fill method. When the method returns, the DataTable instance is populated with the queried data. Note that the HarperDBDataAdapter is slower than the HarperDBDataReader because the Fill method needs to retrieve all data from the data source before returning.

The following example selects the City and CompanyName columns of the Cutomers table:

C#

string connectionString = "Server=127.0.0.1;User=admin;Password=1234;Port=9925;";

using (HarperDBConnection connection = new HarperDBConnection(connectionString)) {
  HarperDBDataAdapter dataAdapter = new HarperDBDataAdapter(
  "SELECT City, CompanyName FROM [HarperDB].[cstest].Cutomers", connection);

  DataTable table = new DataTable();
  dataAdapter.Fill(table);

  Console.WriteLine("Contents of Cutomers.");

  foreach (DataRow row in table.Rows) {
    Console.WriteLine("{0}: {1}", row["City"], row["CompanyName"]);
  }
}

VB.NET

Dim connectionString As String = "Server=127.0.0.1;User=admin;Password=1234;Port=9925;"

Using connection As New HarperDBConnection(connectionString)
  Dim dataAdapter As New HarperDBDataAdapter("SELECT City, CompanyName FROM [HarperDB].[cstest].Cutomers", connection)

  Dim table As New DataTable()
  dataAdapter.Fill(table)

  Console.WriteLine("Contents of Cutomers.")

  For Each row As DataRow In table.Rows
    Console.WriteLine("{0}: {1}", row("City"), row("CompanyName"))
  Next
End Using