LINQ address the current database development model in thecontext of Object Oriented Programming Model. If we want to develop database applicationin .Net platform then there will be very simple approach like we will useADO.NET because it will work as a middleware to connect database, for businesslogic we should be good in C# or VB.NET so overall we should have goodknowledge in both database programming (SQL) and in Object Oriented Programmingbut here SQL statements become the part of C# and VB.NET code  in the form ofLINQ. So we can write database code in C# or VB.NET.

LINQ has a great power of querying on any source of data,data source could be the collections of objects, database or XML files. We caneasily retrieve data from any object that implements the IEnumerable<T> interface. Microsoft divides LINQ into three areas. 

• LINQ to Object {Queries performed against the in-memory data}
• LINQ to ADO.Net
• LINQ to SQL (formerly DLinq) {Queries performed against the relation database only Microsoft SQL Server Supported}
• LINQ to DataSet {Supports queries by using ADO.NET data sets and data tables}
• LINQ to Entities {Microsoft ORM solution}
• LINQ to XML (formerly XLinq) { Queries performed against the XML source}