使用LINQ C#合并2个数据表(包括空行)

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

public class Program
{
    public static void Main()
    {
        // 两个示例数据表
        List<Person> table1 = new List<Person>
        {
            new Person { ID = 1, Name = "Alice" },
            new Person { ID = 2, Name = "Bob" },
            new Person { ID = 3, Name = "Charlie" }
        };

        List<Person> table2 = new List<Person>
        {
            new Person { ID = 2, Name = "Bob" },
            new Person { ID = 4, Name = "David" }
        };

        // 使用LINQ合并两个数据表（包括空行）
        var mergedTable = table1
            .FullOuterJoin(table2, t1 => t1.ID, t2 => t2.ID, (t1, t2) => new { ID = t1?.ID ?? t2?.ID, Name = t1?.Name ?? t2?.Name })
            .ToList();

        // 打印合并后的数据表
        Console.WriteLine("合并后的数据表：");
        foreach (var person in mergedTable)
        {
            Console.WriteLine($"ID: {person.ID}, Name: {person.Name}");
        }
    }
}

public class Person
{
    public int ID { get; set; }
    public string Name { get; set; }
}

public static class LinqExtensions
{
    // 实现Full Outer Join
    public static IEnumerable<TResult> FullOuterJoin<TOuter, TInner, TKey, TResult>(
        this IEnumerable<TOuter> outer,
        IEnumerable<TInner> inner,
        Func<TOuter, TKey> outerKeySelector,
        Func<TInner, TKey> innerKeySelector,
        Func<TOuter?, TInner?, TResult> resultSelector)
    {
        var innerLookup = inner.ToLookup(innerKeySelector);
        var outerLookup = outer.ToLookup(outerKeySelector);

        var keys = new HashSet<TKey>(innerLookup.SelectMany(x => x).Select(innerKeySelector));
        keys.UnionWith(outerLookup.SelectMany(x => x).Select(outerKeySelector));

        return from key in keys
               from innerItem in innerLookup[key].DefaultIfEmpty()
               from outerItem in outerLookup[key].DefaultIfEmpty()
               select resultSelector(outerItem, innerItem);
    }
}