具有Linq和默认值的多个左连接

var leftTable = new List<LeftTableItem>()
{
    new LeftTableItem() { Id = 1, Name = "Item 1" },
    new LeftTableItem() { Id = 2, Name = "Item 2" },
    new LeftTableItem() { Id = 3, Name = "Item 3" }
};

var rightTable = new List<RightTableItem>()
{
    new RightTableItem() { Id = 1, Value = "Value 1" },
    new RightTableItem() { Id = 2, Value = "Value 2" }
};

var query = from leftItem in leftTable
            join rightItem in rightTable on leftItem.Id equals rightItem.Id into temp
            from rightItem in temp.DefaultIfEmpty(new RightTableItem() { Id = 0, Value = "Default Value" })
            select new { leftItem.Name, rightItem.Value };

foreach (var result in query)
{
    Console.WriteLine($"Left Item: {result.Name}, Right Item: {result.Value}");
}