What is LINQ?

- LINQ or Language Integrated Query is a component of Visual Studio that was introduced in 2008. LINQ simplifies creating and executing query expressions. It also provides ways to translate between the representation of data in its source and an object in a .NET application. LINQ interfaces with C# and Visual Basic. In this course, I will be focusing on the former. You can think of LINQ as an extension. LINQ provides methods and tools to easily query data sets of different types.

If I wanted to find a subset of my customers, say those that live in a particular state, I can use a simple LINQ method to do so. It can help me with more complicated queries such as finding customers in a particular state, that have bought a particular product, from a particular distributor with a specific discount. Without LINQ, I would have to iterate over the set with a series of nested and complicated for each loops. The LINQ syntax is easier to create, read and maintain. LINQ can also help when my program needs to interface with an outside data source.

There are many ways to store data. Today, SQL databases, XML documents, and other web services are just a few tools used. Each of these has their own queries and syntax that you can use to interface with their data. It's easy enough to pick up one new tool. Unfortunately, C# applications often need to work with data from multiple sources all at once. It is unfeasible to learn how to interface natively with every new data source. LINQ is a common query language that can interface with a multitude of data sources like SQL, XML, and other services.

This provides a way to extract data from these sources into a .NET application making development much easier. Instead of learning a new syntax to query from each different source, you can use a link extension for each new source. Bottom line, if you are interfacing with data sets in C#, LINQ is a great tool to help you get the job done.