select * from table1 where column1 = 2016 and column2 ='ZY' and column3 not in(select column3 from table2); 2.LINQ中的in和not in用法List<testInfo> listAll = new List<testInfo>(); listAll.Add(new testInfo() { id = 1, name = "11", test = "111" }); listAll.Add(new ...
1.LINQ的IN: var queryResult = from pindb.Products where (newint?[] {1,2}).Contains(p.CategoryID) select p; 2.LINQ的NOT IN: var queryResult = from pindb.Products where !(newint?[] { 1, 2 }).Contains(p.CategoryID) select p; 3.LINQ的NOT IN 遍历集合 List<string> source = n...
(v.FullName); } var queryList2Only = (from file in list2 select file) .Except(list1, myFileCompare); Console.WriteLine(); Console.WriteLine($"The following files are in list2 but not list1 (total number = {queryList2Only.Count()}:"); foreach (var v in queryList2Only...
Dim petOwners = From pers In people Group Join pet In pets On pers Equals pet.Owner Into PetList = Group From pet In PetList.DefaultIfEmpty() Select pers.FirstName, pers.LastName, PetName = If(pet Is Nothing, String.Empty, pet.Name) ' Display "flat"...
薪水大于17000的用户集合,投影存储他们的姓名和职业*/List<User>salary_list=salaryList.Where(u=>u.salary>17000).Select(g=>newUser(){name=g.name,occupation=g.occupation}).ToList();/*取上面两个集合的交集为结果集*/List<User>result_list=user_list.Intersect(salary_list,newCompareUser()).ToList...
Select(i => i * i); GC.Alloc发生在LINQ的内部实现中。此外,一些LINQ方法针对调用者的类型进行了优化,因此GC的大小。根据调用者的类型分配更改。 每种类型的执行速度验证 代码语言:javascript 代码运行次数:0 运行 AI代码解释 private int[] array; private List<int> list; private IEnumerable<int> ...
我正在学习Linq,我有一个情况,我想写我的查询如下 Select ordernumber from orders where ordernumber not in (Select ordernumber from shipdata) 我知道这将在mssqlserver中工作,但我如何在LINQ中编写它呢? 发布于 2 月前 ✅ 最佳回答: 我倾向于使用Lambda语法,因此对查询语法没有太大帮助。我就这样写你...
我将构建一个只包含所需列的新数据表。。。 如果知道要保留哪些列,可以进行选择 dim result = dt.AsEnumerable().[Select](Function(x) New With { Key .Col1 = x.Field(Of String)("Column1"), Key .Col2 = x.Field(Of String)("Column2") }).Tolist() 否则你可以...
var evenNumQuery = from num in numbers where (num % 2) == 0 select num; int evenNumCount = evenNumQuery.Count(); To force immediate execution of any query and cache its results, you can call the ToList or ToArray methods. C# Copy List<int> numQuery2 = (from num in numbers...
var evenNumQuery = from num in numbers where (num % 2) == 0 select num; int evenNumCount = evenNumQuery.Count(); To force immediate execution of any query and cache its results, you can call the ToList or ToArray methods. C# Copy List<int> numQuery2 = (from num in numbers...