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C# program to join Employee and Department class using Linq Join Query

Here, we are going to learn how to join Employee and Department class using Linq Join Query in C#?
Submitted by Nidhi, on September 01, 2020

Here we will create two classes Employee and Department. Then we will join both Employee and Department based on department id using Linq Join Query.

Program:

The source code to join Employee and Department using Linq Join Query, which is given below. The given program is compiled and executed successfully on Microsoft Visual Studio.

//C# program to join Employee and Department 
//class using Linq Join Query.

using System;
using System.Linq;
using System.Collections.Generic;

public class Employee
{
    public int ID;
    public int Salary;
    public int DEPT_ID;
    public string Name;
}

public class Department
{
    public int DEPT_ID;
    public string DEPT_Name;
}

public class JoinDemo
{
    static void Main(string[] args)
    {

        List<Employee> employees = new List<Employee>()
        {
             new Employee {ID=101,   Name="Amit  "    , Salary=4000,DEPT_ID=101},
             new Employee {ID=102,   Name="Amit  "    , Salary=3800,DEPT_ID=102},
             new Employee {ID=103,   Name="Salman"    , Salary=3500,DEPT_ID=103},
             new Employee {ID=104,   Name="Ram   "    , Salary=2000,DEPT_ID=101},
             new Employee {ID=105,   Name="Shyam "    , Salary=7000,DEPT_ID=102},
             new Employee {ID=106,   Name="Kishor"    , Salary=5000,DEPT_ID=103},
        };

        List<Department> departments = new List<Department>()
        {
             new Department {DEPT_ID=101,   DEPT_Name="HR        "   },
             new Department {DEPT_ID=102,   DEPT_Name="ACCOUNTS  "   },
             new Department {DEPT_ID=103,   DEPT_Name="SALES     "   },
        };

        var ResultQuery = (from emp in employees
                           join dept in departments
                           on emp.DEPT_ID equals dept.DEPT_ID
                           select new
                           {
                               ID = emp.ID,
                               Name = emp.Name,
                               Salary = emp.Salary,
                               DeptName = dept.DEPT_Name
                           }).ToList();


        Console.WriteLine("Employee Details: ");
        foreach (var e in ResultQuery)
        {
            Console.WriteLine("\tID: " + e.ID + ", Name: " + e.Name + ", Salary: " + e.Salary + ", Department: " + e.DeptName);
        }
    }
}

Output:

Employee Details:
        ID: 101, Name: Amit  , Salary: 4000, Department: HR
        ID: 102, Name: Amit  , Salary: 3800, Department: ACCOUNTS
        ID: 103, Name: Salman, Salary: 3500, Department: SALES
        ID: 104, Name: Ram   , Salary: 2000, Department: HR
        ID: 105, Name: Shyam , Salary: 7000, Department: ACCOUNTS
        ID: 106, Name: Kishor, Salary: 5000, Department: SALES
Press any key to continue . . .

Explanation:

In the above program, we created three classes Employee, Department, and JoinDemo. Employee class contains data members ID, Name, Salary, and DEPT_ID. The Department class contains DEPT_ID and DEPT_Name.

Now look to the JoinDemo class, the JoinDemo class contains the Main() method. In the Main() method we created a list of employees and departments.

var ResultQuery = (from emp in employees
            join dept in departments
            on emp.DEPT_ID equals dept.DEPT_ID
            select new
            {
                ID = emp.ID,
                Name = emp.Name,
                Salary = emp.Salary,
                DeptName = dept.DEPT_Name
            }).ToList();

In the above code we joined Employee and Department class using join query and select ID, Name, Salary, and DEPT_Name.

Console.WriteLine("Employee Details: ");
foreach (var e in ResultQuery)
{
    Console.WriteLine("\tID: "+e.ID+", Name: "+e.Name+", Salary: "+e.Salary+", Department: "+e.DeptName);
}

The above code will print the result of join on the console screen.

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