C#linq学习资料，精简资源-CSDN文库

共174个文件

dll：128个

cs：12个

cache：9个

需积分: 8 178 浏览量 2022-03-01 17:15:32 上传评论收藏 6.17MB RAR 举报

C# LINQ（Language Integrated Query，语言集成查询）是.NET框架的一个重要组成部分，它为C#程序员提供了一种简洁、高效的查询数据的方式。LINQ允许开发者以一种与数据库查询相似的语法来处理各种数据源，如集合、数组、XML、数据库等。在本资料中，我们将深入探讨C# LINQ的基础概念、核心特性以及高级用法。 1. **基础概念** - **查询表达式**：LINQ的主要特点之一就是引入了查询表达式，这是一种新的语法结构，类似于SQL查询，但适用于任何数据源。例如，`from`关键字用于定义数据源，`where`用于筛选，`select`用于投影结果。 2. **方法语法**：除了查询表达式，还可以使用方法语法进行查询，这种方法更接近于函数式编程风格。例如，`Where()`用于过滤，`Select()`用于转换。 3. **延迟执行与立即执行**：LINQ查询是延迟执行的，这意味着查询操作不会立即执行，而是在需要结果时才执行。这提高了性能，因为可以避免不必要的数据处理。 4. **数据源**：LINQ可以应用于多种数据源，包括内存中的集合、数据库（通过ADO.NET）、XML文档（通过System.Xml.Linq命名空间）等。 5. **查询操作符**： - **聚合操作**：如`Count()`, `Sum()`, `Average()`, `Max()`, `Min()`等，用于对数据进行统计计算。 - **分组操作**：`GroupBy()`用于将数据根据一个或多个键进行分组。 - **排序操作**：`OrderBy()`和`OrderByDescending()`用于升序和降序排序。 - **连接操作**：`Join()`和`GroupJoin()`用于合并两个数据源。 - **选择子操作**：`SelectMany()`用于从多级嵌套的数据结构中提取元素。 6. **扩展方法**：LINQ的核心是通过一系列的扩展方法实现的，这些方法定义在`Enumerable`和`Queryable`静态类中，使得任何实现了`IEnumerable`接口的对象都可以支持LINQ查询。 7. **异步查询**：在C# 5及以上版本，`async`和`await`关键字结合LINQ可以实现异步查询，提高应用程序的响应性。 8. **数据投影**：`Select()`方法是数据投影的关键，可以将源对象转换为任意类型，实现数据的形态转换。 9. **查询优化**：由于LINQ的延迟执行特性，可以在运行时优化查询，比如减少数据库访问次数，或者合并多次数据操作。 10. **实体框架与LINQ**：在ORM（对象关系映射）框架如Entity Framework中，LINQ用于查询数据库，提供了强大的数据库操作能力。通过《20200802Advancen14Course11LinqAdvanced-2》这个课程，你可以深入学习到如何使用LINQ进行复杂查询，理解并掌握这些概念和技巧，提升你的C#编程能力。学习过程中，你可以通过实践示例来巩固理论知识，并逐步熟练运用到实际项目中。

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C# linq学习资料，精简（174个子文件）

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ICSharpCode.NRefactory.dll 1.64MB

ICSharpCode.AvalonEdit.dll 599KB

System.Reflection.Metadata.dll 563KB

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System.Net.Http.dll 194KB

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System.IO.Compression.dll 108KB

netstandard.dll 96KB

Mono.Cecil.Pdb.dll 85KB

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System.ValueTuple.dll 77KB

System.Composition.TypedParts.dll 63KB

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System.Net.Sockets.dll 30KB

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Microsoft.VisualStudio.Validation.dll 29KB

System.Runtime.dll 29KB

System.Runtime.InteropServices.RuntimeInformation.dll 28KB

Mono.Cecil.Rocks.dll 27KB

System.Runtime.Serialization.Primitives.dll 26KB

System.Globalization.Extensions.dll 25KB

System.Composition.AttributedModel.dll 24KB

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System.Runtime.InteropServices.dll 24KB

System.Diagnostics.StackTrace.dll 23KB

System.Xml.XPath.XDocument.dll 22KB

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System.ComponentModel.TypeConverter.dll 22KB

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System.Net.NetworkInformation.dll 22KB

System.Linq.Expressions.dll 22KB

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System.Net.Primitives.dll 22KB

System.Reflection.dll 22KB

System.Threading.dll 22KB

ILSpy.resources.dll 22KB

System.Security.Cryptography.Primitives.dll 21KB

System.Runtime.CompilerServices.VisualC.dll 21KB

System.ComponentModel.EventBasedAsync.dll 21KB

System.ComponentModel.Primitives.dll 21KB

System.Diagnostics.TraceSource.dll 21KB

System.Globalization.Calendars.dll 21KB

System.Diagnostics.Contracts.dll 21KB

System.Reflection.Primitives.dll 21KB

System.Diagnostics.Process.dll 21KB

System.Runtime.Extensions.dll 21KB

System.Xml.XmlDocument.dll 21KB

System.Xml.ReaderWriter.dll 21KB

System.Xml.XmlSerializer.dll 21KB

System.Text.Encoding.dll 21KB

System.Net.Security.dll 21KB

System.Collections.dll 21KB

System.Xml.XDocument.dll 21KB

System.ObjectModel.dll 21KB

System.Diagnostics.TextWriterTraceListener.dll 21KB

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