You can access the same column information about the results of a query that you can for table schemas. See Columns for the columns returned.

Retrieving Result Set Metadata

You can use the GetSchemaTable method of the AmazonS3DataReader to retrieve result set metadata. Call GetSchemaTable after calling ExecuteReader.

Each row of the DataTable describes a column in the query's result.

C#

string connectionString = "AWSAccessKey=a123;AWSSecretKey=s123;";

using (AmazonS3Connection conn = new AmazonS3Connection(connectionString)) {
  AmazonS3Command cmd = new AmazonS3Command("SELECT * FROM Buckets WHERE Name = 'TestBucket'", conn);
  AmazonS3DataReader rdr = cmd.ExecuteReader();
  DataTable schemaTable = rdr.GetSchemaTable();
  foreach (DataRow row in schemaTable.Rows) {
    foreach (DataColumn col in schemaTable.Columns) {
      Console.WriteLine("{0}: {1}", col.ColumnName, row[col]);
    }
  }
}

VB.NET

Dim connectionString As String = "AWSAccessKey=a123;AWSSecretKey=s123;"

Using conn As New AmazonS3Connection(connectionString)
  Dim cmd As New AmazonS3Command("SELECT * FROM Buckets WHERE Name = 'TestBucket'", conn)
  Dim rdr As AmazonS3DataReader = cmd.ExecuteReader()
  Dim schemaTable As DataTable = rdr.GetSchemaTable()
  For Each row As DataRow In schemaTable.Rows
    For Each col As DataColumn In schemaTable.Columns
      Console.WriteLine("{0}: {1}", col.ColumnName, row(col))
    Next
  Next
End Using