linq pdf

This article is organized from the msdn I. Concepts of LINQ:LINQ is short for Language Integrated Query (Language integration query), which is integrated in. netProgramming LanguageThis allows the query expression to get a good syntax check during compilation, rich metadata, and advantages of smart sensing for other strong languages. net Framework Version 3.5 is a groundbreaking innovation that builds a bridge between the object field and the data field. Ii. Background of the emergence of LI

Recently, an article published by Elisa Flasko on MSDN compares the applicable scenarios of LINQ to SQL and LINQ to Entities: Introducing LINQ to Relational Data Http://msdn2.microsoft.com/en-us/library/cc161164.aspx The author points out that the main application scenarios of LINQ to SQL are the rapid development of M

Recently, an article published by ELISA flasko on msdn compares the applicable scenarios of LINQ to SQL and LINQ to entities:Introducing LINQ to Relational DataHttp://msdn2.microsoft.com/en-us/library/cc161164.aspx The author points out that the main application scenarios of LINQ to SQL are the rapid development of Mic

We know that LINQ to Sharepoint is actually converted into calm for access to SharePoint. So how can we know what the calm statement we write is eventually converted.We can use the following methods to achieve our goal. 1. First, create a new class named camldebug in our SharePoint project ,: Calmdebug. CSCodeAs follows: Using System; Using System. Collections. Generic; Using System. LINQ; Us

C # conversion between Dto Linq Expression and Model Linq Expression in the database in ORM, Today, I saw a question in Baidu zhixing. After studying it for a while, I answered: Http://zhidao.baidu.com/question/920461189016484459.html How to convert a dto linq expression to a database object linq expression. It is feas

1. Single Condition queryvar expr = context. "LINQ to SQL");SELECT [Extent1].[ProductID] as [ProductID], [Extent1].[CategoryID] as [CategoryID], [Extent1].[ProductName] as [ProductName], [Extent1].[UnitPrice] as [UnitPrice], [Extent1].[discontinued] as [discontinued] from [dbo].[Product] as [Extent1] WHEREN'LINQ to SQL' = [Extent1].[ProductName]2. Combination criteria Queryvar expr = context. Products "

ArticleDirectory 1. Get start 2. latency mechanism (deferred/lazy execution) 3. subquery) Language Integrated Query is a group of technical names that allow us to write type-safe query statements to query local objects or remote data sets. The premise of using LINQ is that the collection you need to query implements the ienumerable ProgramExtend the implementation of LINQ, for example,

ArticleDirectory Overview of the linq to XML class LINQ to XML learning-2. Overview of LINQ to XML programming overview of the linq to XML class overview of the xattribute class Xattribute indicates an XML Attribute. Xcdata class Xcdata indicates a CDATA text node. Xcomment class Xcomment indicates an X

Hi: The following is a LINQ to JS share, if there is a coincidence is purely coincidental(function () {Array.prototype.first = function (predicate, def) {var l = this.length; if (!predicate) return l? This[0]: def = = null? Null:def; for (var i = 0; i How to use: List.first (function (t) {return T.value.trim () = = City.trim ();});　　JS simulation expands C # LINQ expressions to share

Label: style blog color Io AR for strong SP Div Grouping refers to grouping values or elements in a sequence based on a specific value. LINQ only contains one grouping OPERATOR: groupby. Groupby 1>. Prototype Definition Public static iqueryable 2>. Example VaR expr = from P in context. products Group P by P. categoryid; foreach (VAR item in expr) {foreach (var p in item) {console. writeline (P. productname );}} VaR expr = context. Cities. grou

This article mainly describes attributes-based Linq ing of Linq to SQL. That is, ing database, ing table, ing column, ing relationship, ing stored procedure, Ing function. However, there are three ways to create such mappings: ORD, SQLMetal, and manual code. Create. First, let's understand how to manually create property ing so that you can understand the code generated based on the tool. Their differenc

Combination of Linq groups and linq groups There is a List, which requires grouping by date and combining the data of the same day with the implementation of Linq. namespace ConsoleApplication1{ class Program { static void Main(string[] args) { List We can see that the data items are grouped by date, and the data items of other a

And then, in this section, I'm going to lead you through the rest of the LINQ syntax. OK, no more nonsense, get to the point. 1, Cast, oftype operator Cast and OfType: are used to convert a collection object of type IEnumerable to a collection object of type ienumerable Here's an example from the previous section: (This example is referenced from Rookie_j blog) Create a new ArrayList object first ArrayList ArrayList = new ArrayList () { New Person ()

We use a database of hotel management systems as an exampleTable structure is simple: guestinfo (guest information table), Room (rooms table), Roomtype (room type table), Hotelinfo (monthly earnings information)As a whole, there is a foreign key to the room type ID, and a foreign key for the ID of the room in the guest table. Monthly earnings information regardless of firstPreparation: New Project LINQ_CH4 console program, new DB folderRight-click the DB folder, add → new itemSelect the

Let's go on to the LINQ to SQL statement, which we'll talk about Union all/union/intersect operations and TOP/BOTTOM operations and paging operations and sqlmethods operations.Union All/union/intersect operationScenario: two sets of processing, such as append, merge, take the same items, intersect items and so on.Concat (Connection)Description: Connect a different collection. Do not actively filter the same; delay.1. Simple form:var q = (from C in

Tags: style blog color ar strong SP div on log1. One-to-manyvar expr = context. Products "LINQ to SQL" p.unitprice > 10m) New { p.productid, p.productname });var from inch context. Productswhere"LINQ to SQL" p.unitprice > 10m Selectnew { p.productid, p.productname };SELECT [Extent1].[ProductID] as

1. Anonymous typeBy defining an anonymous type with the keyword VAR, the compiler emits a strong type based on the value of the expression on the right side of the operator.Some basic rules to follow when using anonymous types:◊ An anonymous type must have an initialization value, and the value cannot be null (NULL), because the type is inferred from the initializer;◊ Anonymous types can be used for simple types, or for complex types. When defining a simple type, it is of little value. Compound

Object ID Objects in the Runtime Library have a unique identifier. Two variables that reference the same object actually reference the same instance of this object. After you change a variable, you can see the changes through another variable. The row in the relational database table does not have a unique identifier. Because each row has a unique primary key, no two rows share the same key value. In fact, we usually extract data from the database and put it into another layer, where the app

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 in the following example: 1 class Program2 {3 static void main (string [] ARGs)4 {5 Int []

How to Write a method that does not return a value and accepts the LINQ parameter ., Returned value: linq ///