使用 LINQ 连接两个表并将多条记录作为一行返回

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

public class Program
{
    public static void Main()
    {
        // 定义两个表
        List<Student> students = new List<Student>()
        {
            new Student { Id = 1, Name = "Alice" },
            new Student { Id = 2, Name = "Bob" },
            new Student { Id = 3, Name = "Charlie" }
        };

        List<Score> scores = new List<Score>()
        {
            new Score { StudentId = 1, Subject = "Math", Grade = 90 },
            new Score { StudentId = 1, Subject = "English", Grade = 85 },
            new Score { StudentId = 2, Subject = "Math", Grade = 95 },
            new Score { StudentId = 2, Subject = "English", Grade = 80 },
            new Score { StudentId = 3, Subject = "Math", Grade = 88 },
            new Score { StudentId = 3, Subject = "English", Grade = 92 }
        };

        // 使用LINQ连接两个表并将多条记录作为一行返回
        var result = from student in students
                     join score in scores on student.Id equals score.StudentId into temp
                     select new
                     {
                         student.Id,
                         student.Name,
                         Scores = temp.Select(s => new { s.Subject, s.Grade })
                     };

        // 输出结果
        foreach (var item in result)
        {
            Console.WriteLine($"Student: {item.Id} - {item.Name}");
            foreach (var score in item.Scores)
            {
                Console.WriteLine($"Subject: {score.Subject}, Grade: {score.Grade}");
            }
            Console.WriteLine();
        }
    }
}

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

public class Score
{
    public int StudentId { get; set; }
    public string Subject { get; set; }
    public int Grade { get; set; }
}