Attempt by security transparent method 'System.Web.Http.GlobalConfiguration.get_Configuration()' to access security critical type 'System.Web.Http.HttpConfiguration' failed.

This is one of the common error you may experience while using WEB API. This error normally occurs if you are using older version web API.
So the simple solution to resolve this issue is upgrade your WEB API.
Easiest option to upgrade your WEB API is by using NuGet package manager.

TransactionScope in ASP.NET

This is one of the good feature which will help you when you have to do multiple database operations and you wanted to make sure that all the transaction has to be either committed or roll backed as a single unit of work.
TransactionScope is exactly same as the one we use in database level. But sometimes we may not use transaction at database level if the data/table we are operating is completely different and there is no connections.
Couple of important points you have to remember while using TransactionScope is, TransactionScope class cannot be inherited, also this is part of the System.Transactions which means if you wanted to use the class TransactionScope then first you have to refer to the assembly System.Transactions.

Filtered Index in MS SQL

What is filtered index? What is the benefit of using filtered index? Does filtered index really improves the performance? All these queries will be answered in this article.
Lets start with what is filtered index? A kind of interview question.
Filtered index is an optimized non clustered index. Filtered index is more suitable for the queries which select the data from a well defined subset. Important thing you have to remember about the filtered index is it uses the filter predicate to index only a portion of rows in a table. This is what I have mentioned above that “filtered index is suitable for the queries which select the data from a well defined subset”.
Does the filtered index improve the performance?