LINQ学习(四):From子句
<div id="cnblogs_post_body">说明:查询表达式必须以 from 子句开头。 另外,查询表达式还可以包含子查询,子查询也是以 from 子句开头。SQL命令中from指的是数据表,LINQ中from 子句中引用的数据源的类型必须为 IEnumerable、IEnumerable<T> 或一种派生类型(如 IQueryable<T>)。1.复合from子句
说明:如果一个数据源里面又包含了一个或多个集合列表,那么应该使用复合的from子句来进行查询。
查询分数小于60分学生的姓名和分数:
<div class="cnblogs_code"> class Student { public string Name { get; set; } public List<int> Scores { get; set; } } static void Main(string[] args) { List<Student> students = new List<Student>{ new Student {Name="Terry", Scores=new List<int> {97, 72, 81, 60}}, new Student {Name="AI", Scores=new List<int> {75, 84, 91, 39}}, new Student {Name="Wade", Scores=new List<int> {88, 94, 65, 85}}, new Student {Name="Tracy", Scores=new List<int>{97, 89, 85, 82}}, new Student {Name="Kobe", Scores=new List<int> {35, 72, 91, 70}} }; var query = from student in students from score in student.Scores where score < 60 select new { name = student.Name, score }; foreach (var student in query) { Console.WriteLine("{0},{1}", student.name, student.score); //AI,39 //Kobe,35 } Console.ReadKey(); }
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