Part 1 What is LINQ

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In this video, we will discuss
1. What is LINQ
2. Why should we use LINQ and what are the benefits of using LINQ
3. LINQ Architecture
4. LINQ Providers
5. LINQ to SQL Example

What is LINQ
LINQ stands for Language Integrated Query. LINQ enables us to query any type of data store (SQL Server, XML documents, Objects in memory etc).

Why should we use LINQ and what are the benefits of using LINQ
If the .NET application that is being developed
a) Requires data from SQL Server - Then the developer has to understand ADO.NET code and SQL specific to SQL Server Database
b) Requires data from an XML document - Then the developer has to understand XSLT & XPATH queries
c) Need to query objects in memory (List[Customer], List[Order] etc) - Then the developer has to understand how to work with objects in memory

LINQ enables us to work with these different data sources using a similar coding style without having the need to know the syntax specific to the data source. In our upcoming videos we will discuss querying different data sources using LINQ.

Another benefit of using LINQ is that it provides intellisense and compile time error checking.

LINQ Architecture & LINQ Providers
1. LINQ query can be written using any .NET supported programming language
2. LINQ provider is a component between the LINQ query and the actual data source, which converts the LINQ query into a format that the underlying data source can understand. For example LINQ to SQL provider converts a LINQ query to T-SQL that SQL Server database can understand.

If we misspell table or column names in the SQL Query, we will not know about it at compile time. At run time the page crashes and that's when we will know about this error. Also notice that there is no intellisense when typing table and column names. Misspelled column names when reading from the reader will also cause the same problem. With LINQ we will have intellisense and compile time error checking.

With LINQ we get intellisense. If we misspell the table or column names we will get to know about them at compile time.