Difference between Select and SelectMany in LINQ

Select Vs Select-Many in LINQ: An Overview

In this LINQ Tutorial, you will learn SELECT and SELECT-MANY Operators in LINQ and select and select many Operators with some actual Programming Examples.

Select and Select-Many, both are projection operators, which means, they select values from the list, collection, or other sources. A select operator is used to select values from a collection while a Select-Many operator is used to select values from a collection of collections i.e. nested collection. Select operator produces one result value for every source value while SelectMany produces a single result that contains a concatenated value for every source value. And SelectMany operator flattens IEnumerable<IEnumerable<T>> to IEnumrable<T> i.e. list of list to list.

You can understand Select and SelectMany Operator in LINQ more clearly when you see the actual programming examples.

SELECT OPERATOR EXAMPLE:

using System;
using System.Collections.Generic;
using System.Linq;
 
namespace OperatorTutorial
{
    class SoftwareCompany
    {
        public string employeeName { get; set; }
        public int employeeSalary { get; set; }
        public List employeeDetails { get; set; }
    }
 
    class Program
    {
        static void Main(string[] args)
        {
            var result = from p in GetCompanyDetails()
                         select new { p.employeeName, p.employeeSalary, p.employeeDetails };
            foreach (var r in result)
            {
                Console.WriteLine(r);
            }
            Console.ReadKey();
        }
 
        //Creating List of employee
        static List GetCompanyDetails()
        {
            List employee = new List
            {
            new SoftwareCompany
                {
               employeeName = "Vishnu",
               employeeSalary = 20000,
               employeeDetails = new List{"Software developer","Pune","Maharashtra"}
                },
            new SoftwareCompany
                {
               employeeName = "Priya",
               employeeSalary = 40000,
               employeeDetails = new List{"QA","Mumbai","Maharashtra"}
                },
            new SoftwareCompany
                {
               employeeName = "Jagat",
               employeeSalary = 800000,
               employeeDetails = new List{"Manager","Banglore","Karnataka "}
                },
            };
            return employee;
        }
    }
}

Output:

{ employeeName = Vishnu, employeeSalary = 20000, employeeDetails = System.Collections.Generic.List`1[System.String] }
{ employeeName = Priya, employeeSalary = 40000, employeeDetails = System.Collections.Generic.List`1[System.String] }
{ employeeName = Jagat, employeeSalary = 800000, employeeDetails = System.Collections.Generic.List`1[System.String] }

Explanation:

SELECT MANY OPERATOR EXAMPLE:

using System;
using System.Collections.Generic;
using System.Linq;
 
namespace OperatorTutorial
{
    class SoftwareCompany
    {
        public string employeeName { get; set; }
        public int employeeSalary { get; set; }
        public List employeeDetails { get; set; }
    }
 
    class Program
    {
        static void Main(string[] args)
        {
            var result = from p in GetCompanyDetails()
                         select new { p.employeeName, p.employeeSalary, p.employeeDetails };;
                         
            foreach (var r in result.SelectMany(SoftwareCompany => SoftwareCompany.employeeDetails))
            {
                Console.WriteLine(r);
            }
            Console.ReadKey();
        }
 
        //Creating List of employee
        static List GetCompanyDetails()
        {
            List employee = new List
            {
            new SoftwareCompany
                {
               employeeName = "Vishnu",
               employeeSalary = 20000,
               employeeDetails = new List{"Software developer","Pune","Maharashtra"}
                },
            new SoftwareCompany
                {
               employeeName = "Priya",
               employeeSalary = 40000,
               employeeDetails = new List{"QA","Mumbai","Maharashtra"}
                },
            new SoftwareCompany
                {
               employeeName = "Jagat",
               employeeSalary = 800000,
               employeeDetails = new List{"Manager","Banglore","Karnataka "}
                },
            };
            return employee;
        }
    }
}

Output:

Output:

Software developer
Pune
Maharashtra
QA
Mumbai
Maharashtra
Manager
Banglore
Karnataka 

Explanation:

Summary:

I hope you will enjoy Select and SelectMany while programming with LINQ. I would like to have feedback from my blog readers. Your valuable feedback, questions, or comments about this article are always welcome. Read more articles related to LINQ. Enjoy coding...!