what are difference between dataset and datareader

Introduction

In this tips, explore, what are difference between dataset and datareader.

DataSet:
1. used to retreive data in a disconnected manner.
2. can be serialized and transported to another system (using xml)
3. extremely flexible for manipulating data.

DataReader:
1. used to retreive data in a connected manner, until closed.
2. cannot be serilized, and is used only for read scenarios.

Internal functionning of the dataset:
1. it uses a DataReader to retreive its data, and then disconnect.
2. its structure is persisted in memory or using xml.

in this case, it is useless to use the dataset, in order to fill another structure such as a generic list System.Collections.generic.List, System.Collections.generic.List(Of T).

It is better to use a datareader to fill a generic list.

for more information on this:
perfomance check list for ado.net http://msdn2.microsoft.com/en-us/library/ms998589.aspx
Imporving ADO.NET performance http://msdn2.microsoft.com/en-us/library/ms998569.aspx

Further thoughts : with the entity framework, we have another level of abstraction. Yet, we still need datasets for their many capabilities (caching, compatibility with reporting services, xml data persistance and more...). the DataSet is here to stay for many scenarios.

Finally, the dataset is perfect for implementing the "Data Transfer Object" pattern, which is explained here : http://msdn.microsoft.com/en-us/library/ms978717.aspx

Happy Programming