如何正確實現LINQ語句'從集合中的x'？

Question

我爲一個基本的數據庫做了一個簡單的類來測試我從Microsoft的幫助中心複製出來的LINQ查詢，但遇到了令我困惑的錯誤。該錯誤表示x在當前上下文中不存在。

類的例子：

public class Student 
{ 
    public string First { get; set; } 
    public string Last { get; set; } 
    public int ID { get; set; } 
    public List<int> Scores; 

    List<Student> students = new List<Student> { 
     new Student {First="Svetlana", Last="Omelchenko", ID=111, Scores= new List<int> {97, 92, 81, 60}}, 
     new Student {First="Claire", Last="O'Donnell", ID=112, Scores= new List<int> {75, 84, 91, 39}}, 
     new Student {First="Sven", Last="Mortensen", ID=113, Scores= new List<int> {88, 94, 65, 91}}, 
     new Student {First="Cesar", Last="Garcia", ID=114, Scores= new List<int> {97, 89, 85, 82}}, 
     new Student {First="Debra", Last="Garcia", ID=115, Scores= new List<int> {35, 72, 91, 70}}, 
     new Student {First="Fadi", Last="Fakhouri", ID=116, Scores= new List<int> {99, 86, 90, 94}}, 
     new Student {First="Hanying", Last="Feng", ID=117, Scores= new List<int> {93, 92, 80, 87}}, 
     new Student {First="Hugo", Last="Garcia", ID=118, Scores= new List<int> {92, 90, 83, 78}}, 
     new Student {First="Lance", Last="Tucker", ID=119, Scores= new List<int> {68, 79, 88, 92}}, 
     new Student {First="Terry", Last="Adams", ID=120, Scores= new List<int> {99, 82, 81, 79}}, 
     new Student {First="Eugene", Last="Zabokritski", ID=121, Scores= new List<int> {96, 85, 91, 60}}, 
     new Student {First="Michael", Last="Tucker", ID=122, Scores= new List<int> {94, 92, 91, 91} } 
    }; 
} 

查詢語句：

IEnumerable<Student> studentQuery = 
      from student in **students** this is the error that the compiler told me 'does not exist in the current context' 
      where student.Scores[0] > 90 
      select student; 

Answer 1

你想擁有這樣我相信：

public class Student 
{ 
    public string First { get; set; } 
    public string Last { get; set; } 
    public int ID { get; set; } 
    public List<int> Scores; 
} 

List<Student> students = new List<Student> { 
    new Student {First="Svetlana", Last="Omelchenko", ID=111, Scores= new List<int> {97, 92, 81, 60}}, 
    new Student {First="Claire", Last="O'Donnell", ID=112, Scores= new List<int> {75, 84, 91, 39}}, 
    new Student {First="Sven", Last="Mortensen", ID=113, Scores= new List<int> {88, 94, 65, 91}}, 
    new Student {First="Cesar", Last="Garcia", ID=114, Scores= new List<int> {97, 89, 85, 82}}, 
    new Student {First="Debra", Last="Garcia", ID=115, Scores= new List<int> {35, 72, 91, 70}}, 
    new Student {First="Fadi", Last="Fakhouri", ID=116, Scores= new List<int> {99, 86, 90, 94}}, 
    new Student {First="Hanying", Last="Feng", ID=117, Scores= new List<int> {93, 92, 80, 87}}, 
    new Student {First="Hugo", Last="Garcia", ID=118, Scores= new List<int> {92, 90, 83, 78}}, 
    new Student {First="Lance", Last="Tucker", ID=119, Scores= new List<int> {68, 79, 88, 92}}, 
    new Student {First="Terry", Last="Adams", ID=120, Scores= new List<int> {99, 82, 81, 79}}, 
    new Student {First="Eugene", Last="Zabokritski", ID=121, Scores= new List<int> {96, 85, 91, 60}}, 
    new Student {First="Michael", Last="Tucker", ID=122, Scores= new List<int> {94, 92, 91, 91} } 
}; 

IEnumerable<Student> studentQuery = 
     from student in students 
     where student.Scores[0] > 90 
     select student;