C#-এ LINQ এবং ল্যাম্বডা দিয়ে Join ব্যবহার করার পদ্ধতি

ইনার জয়েন শুধু সেই রেকর্ড বা রো রিটার্ন করে যা উভয় টেবিলে ম্যাচ করে বা অস্তিত্বে থাকে। আমরা কন্ডিশনাল ভিত্তিতে একাধিক টেবিলে জয়েন প্রয়োগ করতে পারি। যদি একাধিক কন্ডিশনে জয়েন প্রয়োগ করতে হয় তবে অনোনিমাস টাইপ ব্যবহার করুন।

নিচের উদাহরণে LINQ-এ জয়েন করার ২টি পদ্ধতি দেখানো হয়েছে। এখানে Department এবং Employee জয়েন করা হয়েছে।

উদাহরণ

class Program
{ 
    static void Main(string[] args)
    { 
        var result = Employee.GetAllEmployees().Join(Department.GetAllDepartments(),
            e => e.DepartmentID,
            d => d.ID,
            (employee, department) => new
            {
                EmployeeName = employee.Name,
                DepartmentName = department.Name
            });
        
        foreach (var employee in result)
        { 
            Console.WriteLine(employee.EmployeeName + "\t" + employee.DepartmentName); 
        } 
        
        var result1 = from e in Employee.GetAllEmployees()
                      join d in Department.GetAllDepartments()
                      on e.DepartmentID equals d.ID
                      select new
                      {
                          EmployeeName = e.Name,
                          DepartmentName = d.Name
                      };
        
        foreach (var employee in result1)
        { 
            Console.WriteLine(employee.EmployeeName + "\t" + employee.DepartmentName); 
        } 
        
        Console.ReadLine(); 
    } 
} 

public class Employee
{ 
    public int ID { get; set; } 
    public string Name { get; set; } 
    public int DepartmentID { get; set; } 
    
    public static List GetAllEmployees()
    { 
        return new List()
        { 
            new Employee { ID = 1, Name = "A", DepartmentID = 1 },
            new Employee { ID = 2, Name = "B", DepartmentID = 2 },
            new Employee { ID = 3, Name = "B", DepartmentID = 1 },
            new Employee { ID = 4, Name = "V", DepartmentID = 1 },
            new Employee { ID = 5, Name = "F", DepartmentID = 2 },
            new Employee { ID = 6, Name = "R", DepartmentID = 2 },
            new Employee { ID = 7, Name = "TT", DepartmentID = 1 },
            new Employee { ID = 8, Name = "YY", DepartmentID = 1 },
            new Employee { ID = 9, Name = "WW", DepartmentID = 2 },
            new Employee { ID = 10, Name = "QQ" }
        }; 
    } 
} 

public class Department
{ 
    public int ID { get; set; } 
    public string Name { get; set; } 
    
    public static List GetAllDepartments()
    { 
        return new List()
        { 
            new Department { ID = 1, Name = "IT" },
            new Department { ID = 2, Name = "HR" },
            new Department { ID = 3, Name = "Contract" }
        }; 
    } 
}

আউটপুট

A IT
B HR
B IT
V IT
F HR
R HR
TT IT
YY IT
WW HR
A IT
B HR
B IT
V IT
F HR
R HR
TT IT
YY IT
WW HR