Table of Contents 1. Use LINQ to operate arrays and collections 2. Use LINQ to operate DataSet data set 1.AsEnumerable() method 2.CopyToDataTable() method 3.AsDataView() method 4.Take() method 5.Sum() method 6.Example (1) Source code (2) Generate effect 3. Use LINQ to operate XML 1.Load() method of XElement class 2.SetAttributeValue() method of XElement class 3.Add() method of […]
Tag: linq
LINQ to Entities does not recognize method ***, so the method cannot be converted to a stored expression
There is this piece of code in my program: order.OrderExpressInfo = (from oei in orderExpressRepository.Entities where oei.OrderId == order.OrderId select new EbcBuy.Bll.Orders.Models.OrderExpress { ContentInfo = oei.ContentInfo, CreatedTime = oei.CreatedTime, CreatedUserId = oei.CreatedUserId, ExpressId = oei.ExpressId, ExpressName = oei.ExpressName, ExpressOrderId = oei.ExpressOrderId, Freight = oei.Freight, Manifest = oei.Manifest, OrderId = oei.OrderId, <em>ReceiverContactInfo </em><em>= new ContactInfoModel() { […]
c# Reinvention (4) Linq Statement
(1) Linq statement Language Integrated Query (LINQ) is a collective name for a family of technologies that integrate query functionality directly into the C# language, using query syntax to filter, sort, and group data sources with minimal code. You can use the same basic query expression patterns to query and transform data in SQL databases, […]
Concurrent high-performance data processing technology of Shengxunwei online customer service system: PLINQ parallel query technology Under review
In my spare time, I developed and maintained a free and open source Shengxunwei online customer service system, which also gained many users. For me, as long as I can get recognition from users, it is my biggest motivation. Recently, the customer service system successfully withstood the stress test organized by the customer on-site and […]
Linq’s SelectMany in C#
1. The first usage public static IEnumerable<TResult> SelectMany<TSource, TResult> (this IEnumerable<TSource> source, Func<TSource, IEnumerable<TResult>> selector); Official explanation: Project each element of the sequence to IEnumerable and merge the resulting sequences into one sequence. Test source code: 1. Write Person class and Dog class class Person { public string Name { set; get; } public int […]
C#Linq and delegate (delegate)
Article directory Preface 1. What is delegation? 1. Definition of delegation 2. Use custom delegates 3. Unique features of anonymous delegation 4. How to trigger methods in delegates 4.Action and Func 5. Change the custom delegate to Action and Func. 2. The composition of Linq? 1. Definition of various methods 2.Definition of Linq method Summarize […]
C#–LINQ to SQL technology for database operation
1. Overview of LINQ to SQL technology LINQ to SQL is a component of the .NET Framework version 3.5 that provides a runtime infrastructure for managing relational data as objects. In LINQ to SQL, the data model of a relational database is mapped to an object model that refers to the objects represented by the […]
C# uses Linq and Loop to calculate the mean and variance of the collection [standard deviation]
Variance【Standard Deviation】 The standard deviation formula is a mathematical formula. The standard deviation is also known as the standard deviation, or the experimental standard deviation, and the formula is as follows: Sample standard deviation = arithmetic square root of variance = s=sqrt(((x1-x)^2 + (x2-x)^2 + ……(xn-x)^2)/n) Population standard deviation=σ=sqrt(((x1-x)^2 + (x2-x)^2 + ……(xn-x)^2)/n ) Note: […]
[C#] Parallel programming practice: using PLINQ (3)
PLINQ is a parallel implementation of Language Integrate Query (LINQ) (P stands for parallel). This chapter will go on to describe various aspects of its programming and some advantages and disadvantages associated with it. This article covers combining parallel and sequential LINQ queries in PLINQ, canceling PLINQ queries, things to consider when using PLINQ for […]
Verify whether the Linq mode joint query of MongoDB is available under .Net
The MongoDB.Driver class library provides support for Linq queries. However, when using Linq for joint query, whether it can be correctly converted to the underlying query statement of MongoDB remains to be verified. Today, I will conduct an experiment to verify it. Output query statement First, by subscribing to the function of MongoClientSettings, the query […]