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C# linq 查询

通过这个对象,可以遍历访问集合类对象中的每一个元素对象 2. DataTable dt = GetDetails().Tables[0]; //获取可用的DataTable// var m = dt.AsEnumerable().Last(); 返回DataTable最后一行DataRow//var m = dt.AsEnumerable().First(); 返回Dat...

Model.dbDataContext db = new Model.dbDataContext(ConnStr); var model = from a in db.A join g in db.G on a.ClassID equals g.ID into m from model in m.DefaultIfEmpty() select new { ID=a.ID, Title=a.Title, ...........................

具体方法如下: 匿名类型的传递 static void Main(string[] args) { var User = GetAnonymous().Cast(new { UserName = "", LastLoginIp = "" }); Console.Write(User.UserName); } static object GetAnonymous() { var User = new { UserName =...

数据源.Where(s => s.Name.IndexOf("张")>=0 --------意义等同於 like '%张%' s.Name.StartsWith("张") -------- 等同於like '张%' s.Name.EndWith("张") -------- 等同於like '%张');

表用数组来表示的 private void button1_Click(object sender, EventArgs e) { var a = new[] { new{ id=1,name="测试"}, new {id=2,name="测试123"} }; var b = new[] { new { id = 1, aid = 1, status_id = 1 }, new { id = 2, aid = 2, stat...

1. 可以用查询结果的 ToList()方法 2. 示例代码如下: using System;using System.Collections.Generic;using System.Linq;using System.Text;namespace ConsoleApplication2{ class Program { static void Main(string[] args) { int[] arr = { ...

你的返回类型是worker Linq 取的值是一匿名类型,不能转换过去。 var work = ...... select new Worker{ id=c.w_Id,.......} return work.firstordefault();

(form x in Table group x by x.Name into G select G.Key).ToArray();

arr != null 改成 arr.count()!=0 var arr = from r in a.USER where r.USERNAME == username.Text select r; 得到的arr类似 list

var value=(from v in db.tbl select v.name).Distinct().ToList();

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