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

Using the SparkSQLDataAdapter

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 SparkSQLDataAdapter is slower than the SparkSQLDataReader 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 Customers table:

C#

string connectionString = "Server=127.0.0.1;";

using (SparkSQLConnection connection = new SparkSQLConnection(connectionString)) {
  SparkSQLDataAdapter dataAdapter = new SparkSQLDataAdapter(
  "SELECT City, CompanyName FROM 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["City"], row["CompanyName"]);
  }
}

VB.NET

Dim connectionString As String = "Server=127.0.0.1;"

Using connection As New SparkSQLConnection(connectionString)
  Dim dataAdapter As New SparkSQLDataAdapter("SELECT City, CompanyName FROM 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("City"), row("CompanyName"))
  Next
End Using