(008)：将多个输入联接到一个输出序列



视频演示：http://u.115.com/file/f2f372f454

可以使用 LINQ 查询来创建包含多个输入序列的元素的输出序列。下面的示例演示如何组合两个内存中的数据结构，但组合来自 XML 或 SQL 或数据集源的数据时可应用相同的原则。假定下面两种类类型：

public class Student
{
    public string FirstName { get; set; }
    public string LastName { get; set; }
    public int ID { get; set; }
    public string Street { get; set; }
    public string City { get; set; }
    public List<int> Scores;
}

public class Teacher
{
    public string FirstName { get; set; }
    public string LastName { get; set; }
    public int ID { get; set; }
    public string City { get; set; }
}

下面的示例演示该查询：

static void Main(string[] args)
{
    // Create the first data source.
    List<Student> Students = new List<Student>()
    {
        new Student {FirstName="Svetlana",
            LastName="Omelchenko", 
            ID=111, 
            Street="123 Main Street",
            City="Seattle",
            Scores= new List<int> {97, 92, 81, 60}},
        new Student {FirstName="Claire",
            LastName="O’Donnell", 
            ID=112,
            Street="124 Main Street",
            City="Redmond",
            Scores= new List<int> {75, 84, 91, 39}},
        new Student {FirstName="Sven",
            LastName="Mortensen",
            ID=113,
            Street="125 Main Street",
            City="Lake City",
            Scores= new List<int> {88, 94, 65, 91}},
    };

    // Create the second data source.
    List<Teacher> Teachers = new List<Teacher>()
    {                
        new Teacher {FirstName="Ann", LastName="Beebe", ID=945, City = "Seattle"},
        new Teacher {FirstName="Alex", LastName="Robinson", ID=956, City = "Redmond"},
        new Teacher {FirstName="Michiyo", LastName="Sato", ID=972, City = "Tacoma"}
    };

    // Create the query.
    var PeopleInSeattle = (from student in Students
                           where student.City == "Seattle"
                           select student.LastName)
                .Concat (from teacher in Teachers
                        where teacher.City == "Seattle"
                        select teacher.LastName);

    Console.WriteLine("The following Students and Teachers live in Seattle:");

    // Execute the query.
    foreach (var Person in PeopleInSeattle)
    {
        Console.WriteLine(Person);
    }

    Console.WriteLine("Press any key to exit.");
    Console.ReadKey();

}