简介: C#学习相关系列之Linq用法---where和select用法(二) 一、select用法Linq中的select可以便捷使我们的对List中的每一项进行操作,生成新的列表。var tt=list.select(p=>p+10); //select括号内为List中的每一项,p+10即为对每一项的操作,即对每项都加10生成新的List 用法实例:...
1. Select Select操作符对单个序列或集合中的值进行投影。下面的示例中使用select从序列中返回Employee表的所有列: //查询语法 var query = from e in db.Employees where e.FirstName.StartsWith("M") select e; 生成的sql: SELECT [Extent1].[EmployeeID] AS [EmployeeID], [Extent1].[LastName] AS [...
select new { Group = g.Key, Member = g }; foreach (var g in list2) { result.InnerHtml += g.Group + "个字符:<br />"; foreach (string s in g.Member) { result.InnerHtml += "--" + s + "<br />"; } } result.InnerHtml += "<br />"; } 运行结果7个字符:--asp.net...
countrycode = listofcountrycodes.Split(','); List<State> statelist = new List<State>(); for (int i = 0; i < countrycode.Length; i++) { _states.AddRange( from states in _objdatasources.StateList() where states.CountryCode == countrycode[i].ToString() select new State { StateNa...
·Select - Select选择;延迟 ·Where - Where查询;延迟 ·OrderBy - 按指定表达式对集合正序排序;延迟 ·OrderByDescending - 按指定表达式对集合倒序排序;延迟 ·GroupBy - 分组;延迟 ·Join - Join查询;延迟 ·GroupJoin - 分组Join查询;延迟 ·以上查询操作符所对应的查询语法 ...
Where(r => r.Wins > 15 && (r.Country == "Brazil" || r.Country == "Austria")). //先计算右侧括号里面的谓词结果,做参数再计算 Select(r => r); //谓词条件是r,也就是没有条件只传一个参数 foreach (var r in racers2) {
我有一个Listof 类型Test,有 4 个properties,List需要根据一些特定条件进行排序。properties以下是class Test示例数据。class Test{ int order; string value; string dept; //... and some others}示例 json:[ { "order":3, "value":"ABC", "dept":"A" }, { "order":2, "value":"XYZ", "dept...
SelectList是ASP.NET MVC框架中的一个类,用于表示下拉列表框的选项。在使用SelectList时,可以通过添加Where条件来筛选出符合条件的选项。下面是一个示例: 代码语言:txt 复制 var filteredList = new SelectList(collection, "ValueField", "TextField", null, "DataField = 'value'"); ...
List<int> numbers = [5,4,1,3,9,8,6,7,2,0];// The query variables can also be implicitly typed by using var// Query #1.IEnumerable<int> filteringQuery =fromnuminnumberswherenumis<3or>7selectnum;// Query #2.IEnumerable<int> orderingQuery =fromnuminnumberswherenumis<3or>7orderbynum...
List<int> numbers = [5,4,1,3,9,8,6,7,2,0];// The query variables can also be implicitly typed by using var// Query #1.IEnumerable<int> filteringQuery =fromnuminnumberswherenumis<3or>7selectnum;// Query #2.IEnumerable<int> orderingQuery =fromnuminnumberswherenumis<3or>7orderbynum...