varlist1 =newList<User>{newUser{UserID=1, Name ="User1",Sex="Male"},newUser{UserID=2, Name ="User2",Sex="Female"}, };varlist2 =newList<User>{newUser{ UserID=2, Name ="User2",Sex="Female"},newUser{ UserID=3, Name ="User3",Sex="Female"}, };varresult =list1.Except...
BinaryExpression comparison=Expression.GreaterThan(property, constant);//构建 Lambda 表达式Expression<Func<Person,bool>> lambda = Expression.Lambda<Func<Person,bool>>(comparison, parameter);//编译表达式树并使用Func<Person,bool> func =lambda.Compile();//测试查询条件varpeople =new[] {newPerson { Nam...
of the listDimfilesByLengDesc =FromfileInfileList _Letfilelength = GetFileLength(file) _Wherefilelength >0_OrderByfilelength Descending _SelectfileDimlongestFile = filesByLengDesc.First Console.WriteLine("The largest file under {0} is {1} with a length of...
Imports System.Collections Imports System.Linq Module Module1 Public Class Student Public Property FirstName As String Public Property LastName As String Public Property Scores As Integer() End Class Sub Main() Dim student1 As New Student With {.FirstName = "Svetlana", .Last...
publicstaticboolPublicInstancePropertiesEqual<T>(thisT self, T to,paramsstring[] ignore)whereT :class{if(self ==null|| to ==null) {returnself == to; }// Selects the properties which have unequal values into a sequence of those properties.varunequalProperties =frompropertyintypeof(T).GetPr...
DimqueryResults =FromcustIncustomersWherecust.Country ="Canada" 另一个功能强大的查询子句是Select子句,它能够从数据源仅返回所选字段。 LINQ 查询返回强类型化对象的可枚举集合。 查询可以返回匿名类型或具名类型的集合。 可以使用Select子句从数据源仅返回单个字段。 执行此操作时,返回的集合类型为该单个字段的类型...
By default, the AutoPage property is true. If you assign a value to the Select property, you must also include all identity columns in the list of properties that is returned in the query. Grouping Data You use the GroupBy property to specify which properties are used to consolidate data ...
Expression.Parameter方法创建一个表示查询参数的表达式,Expression.Property方法创建一个表示属性访问的表达式,Expression.Constant方法创建一个表示常量值的表达式,Expression.Equal方法创建一个表示相等比较的表达式,最后Expression.Lambda方法创建一个表示Lambda表达式的表达式。 这种方法可以用于构建任何类型的动态LINQ查询,只需将...
(fromfileinfileListletlen = GetFileLength(file)wherelen >0orderbylendescendingselectfile) .First(); Console.WriteLine("The largest file under {0} is {1} with a length of {2} bytes", startFolder, longestFile.FullName, longestFile.Length);//Return the FileInfo of the smallest fileSystem....
问如何使用Linq to Objects优化列表中任何添加、删除或更新的项目的检查？EN大多数情况下，你只需要缓存+...