LINQ --- An interesting Technology...

Hello Friends,
Linq is very interesting Technology introduced in .Net Framework 3.5.
LINQ stands for Language Integrated Query.
Over View Of LINQ:

• LINQ provides query functionality directly in C# programming languages as we do in Sql Server
• LINQ queries are language constructs which are similar to any other defined code block, such as methods and class definations.
• We can run LINQ queries against any .NET Framework collection that implements IEnumerable, IEnumerable(T), or any collection that implements an interface that inherits from IEnumerable(T), blocks of XML and XML Documents, SQL Server databases, and ADO.NET datasets.

LINQ Providers:
There are mainly four types of LINQ Providers available:

1. LINQ to Objects
2. LINQ to XML
3. LINQ to SQL
4. LINQ to DataSets

Besides the above four, Other Providers is also supported.
LINQ Queries:
The LINQ query by itself defi nes only the shape and structure of the data returned by the
query, not the actual data. The data is available after executing the query. The process of
targeting a data source with a LINQ query and accessing the data has three stages:
1. The data source
2. Query creation
3. Query execution
The Data SourceThe data source is any .NET Framework collection that implements IEnumerable,
IEnumerable(T), or any collection that implements an interface that inherits from
IEnumerable(T), Blocks of XML and XML Documents, SQL Server databases, and ADO.NET
DataSets.
Query CreationQuery creation is the LINQ query that determines the data to retrieve from the data source.
In addition to the actual data to return, LINQ queries can also specify additional information,
such as sort order, and grouping of the returned data.
The following code shows a LINQ query that returns all buttons on a form:
var buttonsQuery =
from Control buttons in this.Controls
where (buttons is Button)
orderby buttons.Text
select buttons;
The variable that will contain the results of the query is called the range variable. In the
above example, the variable is named buttonsQuery.
Query ExecutionQuery execution is typically deferred until the query is iterated over with a foreach loop. In
the case of aggregate functions, such as Sum, Count, and Average, these queries execute
immediately and do not need to be iterated over.
To force immediate execution of a query, call the ToList or ToArray methods of the query’s
range variable, as shown in the following example.
var buttonsQuery =
from Control buttons in this.Controls
where (buttons is Button)
orderby buttons.Text
select buttons.ToList();
In the example LINQ query shown above, you force the query to execute immediately by
calling buttons.ToList().


Thanks,
Paras Sanghani