How to use Select projection in LINQ?

Ethan Karla 454 24 Sep 2021

How to use Select projection in LINQ and also define an example?

Ethan Karla

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An enthusiastic, adaptive, and fast-learning person with a broad and acute interest in the discovery of new innovative drugs, I particularly enjoy collaborating with scientists from different disciplines to develop new skills and solve new challenges.

1 Answers

Ravi Vishwakarma 26 Sep 2021

In LINQ Select projection operator is used for selecting data from collection or SQL Database. The select operator is the same as the SQL select clause operator.

Syntax in C#

var result = from object-of-collection in collection 

        select object-of-collection ;

var result = from s in student

        select new {new-variable-name = object-of-collection.member, ….. };

var result = collection.Select( argument => argument );

Example.

using System;

using System.Collections.Generic;

using System.Linq;

public class Program

{

 public static void Main()

 {

  List<Student> students = new List<Student>()

  {

  new Student() { StudentId = 1, Name = 'Asu', Marks = 500 },

  new Student() { StudentId = 2, Name = 'Shyam', Marks = 300 },

  new Student() { StudentId = 3, Name = 'Shriyam', Marks = 400 },

  new Student() { StudentId = 4, Name = 'Sunny', Marks = 550 },

  new Student() { StudentId = 5, Name = 'Ram', Marks = 600 },

  new Student() { StudentId = 6, Name = 'Krishna', Marks = 700 },

  new Student() { StudentId = 7, Name = 'Anupam', Marks = 550 }

  };

  // select projection using first sysntax

  var result1= from student in students 

               select student ;

  Console.WriteLine('Using First Syntax :\n');

  result1.ToList().ForEach(item => Console.WriteLine('StudentName is {0}, ID is {1}, and Marks is {2}', item.Name, item.StudentId, item.Marks) );

  var result2 = from student in students

                select new {Name =student.Name,ID = student.StudentId,Marks = student.Marks };

  Console.WriteLine('\nUsing Second Syntax :\n');

  result2.ToList().ForEach(item => Console.WriteLine('StudentName is {0}, ID is {1}, and Marks is {2}', item.Name, item.ID, item.Marks) );

  var result3 = students.Select( student => student);

  Console.WriteLine('\nUsing Select method Syntax :\n');

  result3.ToList().ForEach(item => Console.WriteLine('StudentName is {0}, ID is {1}, and Marks is {2}', item.Name, item.StudentId, item.Marks) );

  Console.ReadLine();

 }

}

class Student

{

public int StudentId { get; set; }

public string Name { get; set; }

public int Marks { get; set; }

}

Output

Using First Syntax :

StudentName is Asu, ID is 1, and Marks is 500

StudentName is Shyam, ID is 2, and Marks is 300

StudentName is Shriyam, ID is 3, and Marks is 400

StudentName is Sunny, ID is 4, and Marks is 550

StudentName is Ram, ID is 5, and Marks is 600

StudentName is Krishna, ID is 6, and Marks is 700

StudentName is Anupam, ID is 7, and Marks is 550

Using Second Syntax :

StudentName is Asu, ID is 1, and Marks is 500

StudentName is Shyam, ID is 2, and Marks is 300

StudentName is Shriyam, ID is 3, and Marks is 400

StudentName is Sunny, ID is 4, and Marks is 550

StudentName is Ram, ID is 5, and Marks is 600

StudentName is Krishna, ID is 6, and Marks is 700

StudentName is Anupam, ID is 7, and Marks is 550

Using Select method Syntax :

StudentName is Asu, ID is 1, and Marks is 500

StudentName is Shyam, ID is 2, and Marks is 300

StudentName is Shriyam, ID is 3, and Marks is 400

StudentName is Sunny, ID is 4, and Marks is 550

StudentName is Ram, ID is 5, and Marks is 600

StudentName is Krishna, ID is 6, and Marks is 700

StudentName is Anupam, ID is 7, and Marks is 550

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How to use Select projection in LINQ?

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