linq to objects

Use LinQ to query data objects, and use linq to implement data objects. As a result of project requirements, I have come into contact with LinQ. After some time of study, I have a simple understanding of LinQ. This article will br

From this article, we should summarize the application of LINQ in practice. The first thing we should summarize is the combination of LINQ to objects, that is, the use of LINQ with program objects. The most typical application object set is to use it with arrays, as shown i

Here is the original source: Simple generalization of LINQ LINQ is the abbreviation for language-integrated query, a newly added language feature in C # 3.0 and VB 9.0 that enables collection-based operations using the built-in query language during programming.ListIf you do not have LINQ, to filter out a user object with an odd ID, you need to crea

support object identifiers? Because anonymous objects do not necessarily have a primary key. Linq to SQL, which identifies an entity object through the primary key of the entity, is not created until the data is loaded from the database, and the cache is retrieved based on the primary key for the object that already exists. What kind of problem does this cause? Execute the following code.var c1 = db. Categ

This article is translated from Jon Skeet's blog series "edulinq ". Address: http://msmvps.com/blogs/jon_skeet/archive/2010/09/03/reimplementing-linq-to-objects-part-1-introduction.aspx About a year and a half ago, I gave a speech at the DDD campaign. At that time, I tried to re-implement LINQ to objects. How mu

structure that represents executable code. So why do we need to convert a query expression from a LINQ to SQL statement to an Expression Tree? A linq to SQL query is not executed in the C # program, but is converted into an SQL statement, sent over the network, and finally executed on the database server. That is to say, the following LINQ query is not executed

Document directory Chapter 1 Introduction to LINQ There are a few articles about LINQ in the garden, so I want to create a series. Let's take a look at how to use LINQ to Objects. Here, the blogger is reading "LINQ to Objects

LINQ to objects Data Source Text / Yan zhongcheng In the architecture of LINQ to objects, as long as the objects that implement the ienumerable Differences Description Ienumerable 1. Type struct columns, such as string [], int [], datetime [], and

not equal. Why do anonymous objects not support object identities? Because the anonymous object does not necessarily have a primary key. Linq to SQL identifies an entity object through the primary key of the entity, and when the data is loaded from the database, the primary key is used to retrieve the existing object from the cache before the object is created. What kind of problem does this cause? Execut

Original article:Http://blogs.msdn.com/csharpfaq/archive/2009/03/25/how-to-use-linq-methods-to-compare-objects-of-custom-types.aspx Translation:Http://www.cnblogs.com/tianfan/ LINQ provides a convenient syntax and incluuseful methods for operating with collections of objects. However, to be correctly processed by

This article requires some understanding of LINQ, LAMBDA expressions, and Delegates in C #. At work, you often encounter scenarios that require a comparison of two sets, such as: Page collection data modifications that need to be saved to the database Full synchronization of upstream data to the system database In these scenarios, you need to identify the data that needs to be added, updated, deleted, and because each applicatio

Is there a code everywhere in your program: Db. Customers.insertonsubmit (customer);Db. Submitchange (); If one day, because the database of the Customers table is huge, you need to split it into two tables, whether you will be frightened??? Of course, for queries, we can solve them through views. For inserts, or updates? It is said that in some cases, the current database can be updated and inserted into the view for data. But we have to consider the situation is not possible. Do you have to

An anonymous object is a new mechanism for c#3.0, which uses the new keyword and an initializer for an object to create an anonymous object. As the name implies, this object is an anonymous type object when created, with no specific type. When it comes to anonymous objects, the var keyword we talked about earlier comes in handy. Because you do not know the exact type of the object, you can only declare an object with Var.1 usingSystem;2 usingSystem.Co

This article is translated from Jon Skeet's blog series"Edulinq". Original article address: Http://msmvps.com/blogs/jon_skeet/archive/2010/12/27/reimplementing-linq-to-objects-part-9-selectmany.aspx The following operator is implemented:The most important operator. Majority (or all ?) Other operators that return a sequence can callSelectworkflow. Now let's implement it first. SelectworkflowWha

When it comes to LINQ returning a result set, we typically do this:var result= from in db. Students in db. Classes on S.classid equals c.classid Selectnew { = s.id, = c.name, = c.address };View CodeWe then manipulate the result set directly or further into the entity object.Now we can get

The last time we talked about how to retrieve array content from linq. Since net2.0 and later, generics have become a common application technology. For example, if the list type is supported, the example is as follows: Class Program{Static void Main (string [] args){List New Books {Id = 1, Name = "book1 "},New Books {Id = 2, Name = "book2 "},New Books {Id = 3, Name = "book3 "}};Var book = samplebooks. Where (p => p. Name. Contains ("2 ")). Select (p

classA { Public intID {Get;Set; } Public stringName {Get;Set; } } classB { Public intID {Get;Set; } Public intAge {Get;Set; } } classC { Public intID {Get;Set; } Public stringAddress {Get;Set; } } Private voidButton8_click (Objectsender, EventArgs e) {ListNewList(); ListNewList(); ListNewList(); for(inti =0; I Ten; i++) {Lista.add (NewA () {id = i, name ="name"+i.tostring ()}); Listb.add (NewB () {id = i, age = -+i}); Listc.add (NewC () {id = i, address ="Address"+i.tost

value of the specified sequence length by querying the top n itemsTakeWhile:Skip:SkipWhile:Element operator:First:FirstOrDefault:Last:LastOrDefault:Single: Select a specific and unique item from the meta sequenceSingleordefault:ElementAt: Extracting specific items from a sequenceElementatordefault:Defaultorempty: Returns a default element for an empty sequence, a left-hand inoculation, which can be assigned a default value in place of a possible null valueOther operators:Contact: Appends a sequ

Translated fromJon SkeetSeries of blog posts"Edulinq". Original article address: Http://msmvps.com/blogs/jon_skeet/archive/2010/12/24/reimplementing-linq-to-objects-part-6-repeat.aspx The topic of this article is irrelevant,Repeat. AboutRepeat.EmptyLess. Write this blog to ensure the integrity of this series. RepeatWhat is it? RepeatIt is a static generic method, not an extens

LINQ provides two query syntaxes: query expression and query method syntax. This article is summarized in the following aspects. 1. A simple example containing two query syntaxes 2. query the expression Structure 3. query method-related operatorsA simple example containing two query syntaxes You can use either a query expression or a query method for a LINQ query. You can also combine the two types of queri