Learning LINQ Made Easy

For example if a LINQ query is written to fetch data from SQL Server then the provider LINQ to SQL will convert the underlying query into a Transact SQL that can be understood by the SQL Server database.

Sample Code

// Linq TO SQL  
  
var employees = from listempoyees in context.tblEmployees  
select listempoyees;  
GridView1.DataSource = employees;  
GridView1.DataBind();  
  
// Linq to In memory Object   
// string Array as sample  
  
string[] LstCity = {"Mumbai", "Delhi" , "Patna","London","Banglore","Newyork" };  
  
var cities = from cityList in LstCity  
select cityList;  
  
GridView1.DataSource = cities;  
GridView1.DataBind();

MSDN says that the Query expression consists of the following three clauses:

• FROM
• WHERE
• SELECT

The query variable itself takes no action and returns no data. It just stores the information that is required to produce the results for when the query is executed.

All LINQ query operations consist of the following three distinct actions:

• Obtain the data source.

  string[] LstCity = {"Mumbai", "Delhi" , "Patna","London","Banglore","Newyork" };  

• Create the query.

  var cities = from cityList in LstCity  
  select cityList; 

• Execute the query.

  // 3. Query execution.   
  foreach (int c in cities)  
  {  
     Console.Write("{0,1} ", c);  
  } 

Advantages of LINQ

• LINQ can be used for querying multiple data sources such as relational data and XML data.
• LINQ has syntax highlighting and IntelliSense that help to identify compile-time error checking.
• LINQ is extensible so new types of data sources can be made querable.
• LINQ is composable in nature and it can be used to solve complex problems into a series of short, comprehensible queries that are easy to debug.
• LINQ is declarative, it is very easy to understand and maintain.

Disadvantages of LINQ

• LINQ architecture has another layer for LINQ providers that will provide performance overhead sometimes with complex queries.
• LINQ is not a precompiled statement like Stored Procedures.
• Frequent changes must be recompiled and have a deployment overhead for the entire code.
• No good way to view permissions.
• When database queries are converted from SQL to the application side, joins are very slow that are very specific to LINQ to SQL.

Conclusion

There are many advantages and disadvantages of using LINQ technology. It is very important to choose very intelligently the LINQ for your application so that the beautiful features of LINQ can be utilized and the application can be more efficient. It should not be a performance overhead and problem for your application.

More tutorials on LINQ will be coming shortly.

Keep smiling and keep learning.

References: Introduction to LINQ Queries (C#).