Here is short tutorial only about the difference DataSet, DataReader, DataAdapter and DataView in .net.

1. DataSet

Dataset is connection-less oriented, that means whenever we bind data from database it connects indirectly to the database and then disconnected. It has read/write access on data tables. It supports both forward and backward scanning of data.

DataSet is a container of one or more DataTable. More often than not, it will just contain one table, but if you do a query with multiple SELECT statements, the DataSet will contain a table for each.

You have to be careful about how much data you pull into a DataSet, because this is an in-memory representation. You can Fill a DataSet using the Fill() method of a DataAdapter.

You can download example code at the end of this tutorial!

2. DataReader

DataReader is connection-oriented, that means whenever we bind data from database it must require a connection and after that disconnected from the connection. It has read-only access, we can’t do any transaction on them. It supports forward-only scanning of data, in other words you can’t go backward.

DataReader fetches one row at a time so very less network cost as compare to DataSet(that fethces all the rows at a time). It is scalable to any number of records, at least in terms of memory pressure, since it only loads one record at a time. One typical way to get a DataReader is by using theExecuteReader() method of a DbCommand.

You can download example code at the end of this tutorial!

3. DataAdapter

DataAdapter is an ADO.NET Data Provider. DataAdapter can perform any SQL operations like Insert, Update, Delete, Select in the Data Source by using SqlCommand to transmit changes back to the database.

DataAdapter provides the communication between the Dataset/DataTable and the Datasource. We can use the DataAdapter in combination with the DataSet/DataTable objects. These two objects combine to enable both data access and data manipulation capabilities.

You can download example code at the end of this tutorial!

4. DataView

Generally, we use DataView to filter and sort DataTable rows. So we can say that DataView is like a virtual subset of a DataTable. This capability allows you to have two controls bound to the same DataTable, but showing different versions of the data.

For example, one control may be bound to a DataView showing all of the rows in the table, while a second may be configured to display only the rows that have been deleted from the DataTable. The DataTable also has a DefaultView property which returns the default DataView for the table.

With more and more people and companies developing websites by Microsoft .NET technology, ASP.NET 4.5 shared web hosting comes to be the major solution provided by many web hosting companies. Most of people choose an ASP.NET 4.5 web host considering about .NET framework version, ASP.NET MVC support, SQL Server database, disk space or bandwidth but they usually ignore the most important feature “IIS security level”. That determines whether the ASP.NET 4.5 websites can run successfully on the shared web host. In result to, if you developing an ASP.NET 4.5 website that works well in the local development environment and attempt to run it in the ASP.NET 4.5 shared web host, you may get the following exception,

System.Security.SecurityException: That assembly does not allow partially trusted caller

This is caused by the security level of the ASP.NET 4.5 shared web host that your application is forced to run with the limited permission, by locking down the access to server file system, preventing the background threads, or interacting with COM interfaces, etc.

ASP.NET 4.5 Web Hosting Trust Levels

This security level is known as the Trust Level of IIS for ASP.NET 4.5 websites. 

It can be configured with the following setting:

• Full Trust: website can do everything that the account of the application pool can do on the web server. This is the most flexible configuration for running websites on the shared web hosts. You won’t have any problems unless your website accesses the system information.
• High Trust: websites are limited to call unmanaged code, e.g. Win32 APIs, COM interop.
• Medium Trust: websites are limited to access the file system except the website application directory, system registry, Code DOM, and more (we will talk it later), compared to High Trust.
• Low Trust & Minimal Trust: these two options restrict the websites seriously. Even they don’t allow websites to call the service out of process, such as database, network, etc. But we never saw an ASP.NET 4.5 shared web host configured with either one of these two options.

Full Trust and Medium Trust are two widely used levels in ASP.NET 4.5 shared web hosting. The full trust provides best flexibility but it has potential security issues to the shared server, especially when the web hosting provider doesn't have rich experience on setting up Windows permission and IIS. Compared to Full Trust, you have to review the website carefully before you go with a web host only supports Medium Trust Level. You can refer to the following checkpoints for the review,

• The website shall not call unmanaged APIs.
• The website shall not access to file system, system registry, event logs and anything else related to the system.
• The website shall not generate code for execution dynamically using Code DOM.
• The website shall not use XslTransform to transform something from XML using XSLT.
• The website has to be signed with a Strong Name.

Check with the web page from Microsoft about which namespaces and classes are not supported in Medium Trust environment. 

And here is quick way to confirm the compatibility of websites to Medium Trust Level, in the local environment,

1. Add partially trusted callers attribute into AssemblyInfo.cs file of the website project, as following code snippet,

[assembly: AllowPartiallyTrustedCallers]

2. Add the following line into the web.config,

<trust level="Medium" />

Suggestion

It's a tradeoff between these two trust level. But if you confirm that the website can run successfully with Medium Trust in your local environment, we suggest you choose an ASP.NET 4.5 web host with Medium Trust only. It shall be more secure and reliable anyway. If you host the website based on 3rd party framework such as DotNetNuke, or using 3rd party component, we recommend you going with Full Trust web host.