what is the difference between .net2.0 and .net3.5

The .NET Framework 3.0 is Microsoft's managed code programming model. It is a superset of the .NET Framework 2.0, combining .NET Framework 2.0 components with new technologies for building applications that have visually stunning user experiences, seamless and secure communication, and the ability to model a range of business processes. In addition to the .NET Framework 2.0, it includes Windows Presentation Foundation (WPF), Windows Workflow Foundation (WF), Windows Communication Foundation (WCF), and Windows CardSpace.

Net 3.0 is an add-on to .Net 2.0. It contains three
Libraries for Windows
Presentation Foundation (WPF), Windows Workflow Foundation
(WF) and Windows
Communication Foundation (WCF) (and Windows Cardspace).
You can use these in
Visual Studio 2005 by adding extensions.

.Net 3.5 is the next .Net version after 2.0 shipped with
Visual Studio 2008


.NET 3.5 has LINQ, ASP.NET AJAX, new controls, richer WCF support, and a few other features that aren't in .NET 3.0. For server/asp.net scenarios I'd probably always recommend going with .NET 3.5. For client scenarios, .NET 3.0 is interesting to target since is pre-installed on all versions of Windows Vista - so you have good deployment of the runtime.


Note that all applications that target .NET 3.0 or .NET 2.0 will work run on .NET 3.5. You can't use the new features in .NET 3.5 if you target .NET 3.0 - but your application will obviously still work

What are the differences between Dataset and DataReader

Dataset is in memory representation of the Database. where 

you can create tables, relations between tables, add 

primary key to tables and also manipulate the data 

retrieved form the database. It allows us to work in 

connection less environment.

Datareader is like forward only readonly cursor, which is 

used to retrieve data. data manipulation is not possible 

while using datareader. datareader continously keeps the 

connection open.

A ds (dataset) can be used when the connection is closed.

A dr (datareader) needs the connection open to be used.

A ds can be used to modify or delete or insert data in the 

database. 

A data reader can be used only to read data

A ds can let you access the info on any order at any time.

A dr lets you access the info only one time per item and 

only in a sequential order.

A ds data can be loaded in longer time than a dr can be 

loaded at.

A ds can contain separated and structured data from several 

database tables. 

A dr can contain data in one register per item, that 

register can include data from serveral tables id the sql 

select statement so indicates, but it has no separate 

structure per table.