上面的第一种方法叫查询语法(query syntax),看上去和SQL的语句很相似。查询语法使用查询表达式书写。第二种方法叫方法语法(method syntax)是命令形式,它使用的是标准的方法调用,方法是一组叫做标准查询运算符的方法。虽然形式上这两种查询方法不同,事实上这两种方法存在着紧密的联系,在CLR内只识别查询方法,因此在每次...
Join 和 GroupJoin 运算符旨在高效处理本地查询并支持内部和左外部联接。 Zip 运算符逐步枚举两个序列,对每个序列应用一个函数元素对。 Zip 运算符没有将类型参数命名为 TOuter 和 TInner,而是将它们命名为 TFirst 和 TSecond: IEnumerable<TFirst>、IEnumerable<TSecond>→IEnumerable<TResult> Join、GroupJoin、Zi...
一、简介 //语言集成查询/Query Syntaxvarquery=fromrinstudentswherer.score<60orderbyr.scoreselectr;//链式方法查询/Method Syntaxvarquery2=students.Where(r=>r.score<60).OrderBy(r=>r.score).Select(r=>r);//上面两种linq查询语法是等价的 LINQ(Language Integrated Query)即“语言集成查询”,于2007年...
int[] numbers = [ 5, 10, 8, 3, 6, 12 ]; //Query syntax: IEnumerable<int> numQuery1 = from num in numbers where num % 2 == 0 orderby num select num; //Method syntax: IEnumerable<int> numQuery2 = numbers.Where(num => num % 2 == 0).OrderBy(n => n); foreach...
//Using Query Syntax Console.WriteLine("方式一:"); var GroupByMultipleKeysQS = from std in Student.GetAllStudents() group std by new { std.Branch, std.Gender } into stdGroup orderby stdGroup.Key.Branch descending, stdGroup.Key.Gender ascending select new { Branch = stdGroup.Key.Branch,...
classPet{publicstringName {get;set; }publicintAge {get;set; } }// Uses method-based query syntax.publicstaticvoidGroupByEx1(){// Create a list of pets.List<Pet> pets =newList<Pet>{newPet { Name="Barley", Age=8},newPet { Name="Boots", Age=4},newPet { Name="Whiskers", Age=1...
In query expression syntax, agroup by(C#) orGroup By Into(Visual Basic) clause translates to an invocation ofGroupBy. The translation of the query expression in the following example is equivalent to the query in the example above. C#
();/* Query Expression */// A query expression operates on one or more data sources by applying one or more query operators// The syntax contains SQL-like operators: 'from', 'where', and 'select'// from: defines the source of the data// programmingLanguage: references each iterated ...
ExceptBy 第一个 FirstOrDefault GroupBy GroupJoin 索引 相交 IntersectBy 联接 上一个 LastOrDefault LongCount 最大值 MaxBy Min MinBy OfType 订单 OrderBy OrderByDescending OrderDescending Prepend 范围 Repeat Reverse Select SelectMany SequenceEqual ...
classPet{publicstringName {get;set; }publicintAge {get;set; } }// Uses method-based query syntax.publicstaticvoidGroupByEx1(){// Create a list of pets.List<Pet> pets =newList<Pet>{newPet { Name="Barley", Age=8},newPet { Name="Boots", Age=4},newPet { Name="Whiskers", Age=1...