C# program to join Employee and Department class 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.