LINQ is a language construct that allows one to use an SQL-like syntax to sort, filter and otherwise rearrange a group of objects of a similar type.
From the Microsoft documentation:
LINQ makes a query a first-class language construct in C# and Visual Basic. You write queries against strongly typed collections of objects by using language keywords and familiar operators. The following illustration shows a partially-completed LINQ query against a SQL Server database in C# with full type checking and IntelliSense support.
The title "Link To X" refers to the ability to use LINQ to query a data source of type X, e.g. LINQ to SQL, LINQ to XML, etc.
WRT fetching data from a SQL database, you will first need a DataContext. This establishes the source for your data. Then you need some classes that are representative of your tables. Then you can do this:
IQueryable<customer> custQuery =
from cust in Customers
where cust.City == "London"
select cust;
Start here:
http://msdn.microsoft.com/en-us/library/bb386940.aspx[
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