22-01-2013, 04:31 PM
Linq(Language Integrated Query)
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Introduction
LINQ makes the concept of querying a first-class programming concept in .NET. The data to be queried can take the form of XML (LINQ to XML), databases (LINQ-enabled ADO.NET: LINQ to SQL, LINQ to Dataset and LINQ to Entities) and objects (LINQ to Objects). LINQ is also highly extensible and allows you to build custom LINQ enabled data providers (e.g.: LINQ to Amazon, LINQ to NHibernate, LINQ to LDAP).
LINQ
Linq is the Microsoft's first attempt to integrate queries into language. We know, it is really easy to find data from sql objects simply writing a query while its somewhat hectic when we want to do the same thing in a DataTable or Lists. Generally we will have to loop through every elements to find the exact match, if there is some aggregation we need to aggregate the values etc. Linq provides an easy way to write queries that can run with the in memory objects.
Types of LINQ
Linq Comes with 3 Basic Types (Provided there are lots of more types of LINQ on different type of objects :
1. LINQ (Linq to Objects)
2. DLINQ (Linq to SQL)
3. XLINQ (Linq to XML)
Extension Methods
Another new concept that comes with .NET 3.5 is the Extension methods. Now we can include our own custom methods in already defined objects. We can create static classes and include custom methods to objects. Extension method behavior is similar to that of static methods. You can declare them only in static classes. To declare an extension method, you specify the keyword this as the first parameter of the method. Let us look at the following example: