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

Using the PrestoDataAdapter

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 PrestoDataAdapter is slower than the PrestoDataReader because the Fill method needs to retrieve all data from the data source before returning.

The following example selects the Id and Name columns of the Customers table:

C#

string connectionString = "Server=127.0.0.1;Port=8080;";

using (PrestoConnection connection = new PrestoConnection(connectionString)) {
  PrestoDataAdapter dataAdapter = new PrestoDataAdapter(
  "SELECT Id, Name FROM [Hive].[Default].Customers", connection);

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

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

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

VB.NET

Dim connectionString As String = "Server=127.0.0.1;Port=8080;"

Using connection As New PrestoConnection(connectionString)
  Dim dataAdapter As New PrestoDataAdapter("SELECT Id, Name FROM [Hive].[Default].Customers", connection)

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

  Console.WriteLine("Contents of Customers.")

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