在C#中，使用LINQ（Language Integrated Query）和Lambda表達式可以輕松地實現數據連接

首先，假設我們有兩個類，一個是Student，一個是Teacher。這兩個類分別包含學生和老師的信息。

public class Student
{
    public int Id { get; set; }
    public string Name { get; set; }
    public int TeacherId { get; set; }
}

public class Teacher
{
    public int Id { get; set; }
    public string Name { get; set; }
}

現在，我們需要創建兩個列表來存儲學生和老師的數據。

List<Student> students = new List<Student>
{
    new Student { Id = 1, Name = "Alice", TeacherId = 1 },
    new Student { Id = 2, Name = "Bob", TeacherId = 2 },
    new Student { Id = 3, Name = "Charlie", TeacherId = 1 }
};

List<Teacher> teachers = new List<Teacher>
{
    new Teacher { Id = 1, Name = "Mr. Smith" },
    new Teacher { Id = 2, Name = "Mrs. Johnson" }
};

接下來，我們將使用LINQ和Lambda表達式實現數據連接。在這個例子中，我們將根據TeacherId連接students和teachers列表。

using System.Linq;

var joinedData = students.Join(
    teachers,
    student => student.TeacherId,
    teacher => teacher.Id,
    (student, teacher) => new
    {
        StudentName = student.Name,
        TeacherName = teacher.Name
    });

最后，我們可以遍歷joinedData并輸出結果：

foreach (var item in joinedData)
{
    Console.WriteLine($"Student: {item.StudentName}, Teacher: {item.TeacherName}");
}

這將輸出以下結果：

Student: Alice, Teacher: Mr. Smith
Student: Bob, Teacher: Mrs. Johnson
Student: Charlie, Teacher: Mr. Smith

這就是如何使用C# LINQ和Lambda表達式實現數據連接的方法。