如何用C# LINQ和Lambda实现数据连接

在C#中，使用LINQ（Language Integrated Query）和Lambda表达式可以轻松地实现数据连接

首先，假设我们有两个类，一个是Student，一个是Teacher。这两个类分别包含学生和老师的信息。

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; }
}

现在，我们需要创建两个列表来存储学生和老师的数据。

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" }
};

接下来，我们将使用LINQ和Lambda表达式实现数据连接。在这个例子中，我们将根据TeacherId连接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，我们可以遍历joinedData并输出结果：

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

这将输出以下结果：

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

这就是如何使用C# LINQ和Lambda表达式实现数据连接的方法。