您可以使用 任意且序列相等 为了这个。
Var q= from c in db.Customers where c.Country==”UK”||c.Country==”USA” select new {c.CustomerID,c.CompanyName,phone=c.Phone,InternationalPhone=PhoneNumberConverter ( c.Country,c.Phone)}; PhoneNumberConverter方法如下: public string PhoneNumberConverter(string Country, string Phone) { Pho...
Besides the strongly typed syntax, LINQ queries also have an arsenal of standard query operators to enhance their functionality. These standard query operators operate on sequences and allow you to perform operations such as determining if a value exists in the sequence and performing an aggregated ...
NET to check if user is authorized to view application best way & esieast way to Render partial view ON button click(Jquery) best way for display Description of enum field in list Best way to create a short URL like tiny Url does in MVC ? Best way to display an Access Denied message...
Active Directory problem: Check if a user exists in C#? Active Directory User does not assign User logon name and User Principal Name AD LDS cannot ChangePassword, but it can SetPassword Add <?xml version="1.0" encoding="UTF-8" standalone="yes"?> to my xml response Add a Constraint ...
{ foreach (T item in this) { if (value) item.PropertyChanged += OnItemChanged; else item.PropertyChanged -= OnItemChanged; } tracking = value; } } void OnItemChanged(object sender, PropertyChangedEventArgs e) { if (!Tracking) return; ITrackable item ...
var q = from c in db.Customers select c.ContactName;注意:这个语句只是一个声明或者一个描述,并没有真正把数据取出来,只有当你需要该数据的时候,它才会执行这个语句,这就是延迟加载(deferred loading)。如果,在声明的时候就返回的结果集是对象的集合。你可以使用ToList() 或ToArray()方法把查询结果先进行...
Returns the only element of a sequence that satisfies a specified condition, and throws an exception if more than one such element exists. Single<TSource>(IEnumerable<TSource>) Returns the only element of a sequence, and throws an exception if there is not exactly one element in the sequenc...
you can create a list ofFileInfoobjects to use as a data source. If you try to access theLengthproperty in a query, theFileInfoobject tries to access the file system to update the value ofLength. If the file no longer exists, you get aFileNotFoundExceptionin your query, even though ...
DimitemCount = _ Enumerable.Count(results, _Function(prod) prod.CategoryID =3) You can also call Count as if it were an instance method on the collection itself. When you call the extension method this way, you don't need to supply the first parameter: ...