Querying Using the DataReader

RSSBus ADO.NET Provider for Amazon SimpleDB offers two ways to retrieve data from SimpleDB: SimpleDBDataAdapter objects and SimpleDBDataReader objects. Each object accomplishes the same task -- retrieving data -- but does so in a different way. Whereas SimpleDBDataAdapter objects retrieve all the data that matches a query wholesale, SimpleDBDataReader objects fetch data in subset increments as they are needed.

Using The SimpleDBDataReader

In this example, we use a SimpleDBDataReader to get data from SimpleDB. The SimpleDBDataReader retrieves data faster than the SimpleDBDataAdapter because it can retrieve data in pages. As you read data from the SimpleDBDataReader, it will periodically request the next page of results from the data source if required. This causes results to be returned at a faster rate. The example below selects all the columns from the Lead table:

C#

SimpleDBCommand cmd = new SimpleDBCommand("SELECT * FROM Lead", connection);
  
SimpleDBDataReader rdr = cmd.ExecuteReader();

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

VB.NET

Dim cmd As New SimpleDBCommand("SELECT * FROM Lead", connection)

Dim rdr As SimpleDBDataReader = cmd.ExecuteReader()

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