101 LINQ Samples in C# How to improve your LINQ query performance by 5 X times? Download source code - 849 KB Table of contents Introduction and goal LINQ has been criticized by many early adopters for its performance issues. Well, if you are just going to drag and drop using a DBML code generator, I am sure you will land up in a mess. Try doing this, make a simple LINQ to SQL project using DBML and see your SQL profiler. In this article, we will first look into how LINQ queries are executed, and then we will touch base on how compiled LINQ queries can help us improve our application performance at least 5 times. Still new to LINQ? This article requires some pre-requisites, in case you are new to LINQ I would suggest you to go through the below links. Are you a complete newbie: LINQNewbie.aspxLINQ FAQ Part II: LINQFAQPart2.aspxWant to define 1-* and *-1 using LINQ: OneManyandOneOneLINQ.aspxIssues of multiple trips handled in this article: OptimizingLINQ.aspxDo not know how to call Stored Procedures using LINQ: 6stepsLINQ.aspx Deep dive into how LINQ queries work.
Join Operator. LINQ Examples. Array Class Collections File Keyword String .NET ASP.NET Cast Compression Data Delegate Directive Enum Exception If Interface LINQ Loop Method Number Process Property Regex Sort StringBuilder Struct Switch Time Windows WPF Imperative code describes how to complete an algorithm step-by-step. Declarative code instead describes the end result of that algorithm. LINQ is a declarative syntax form. It makes some computational tasks easier. Intro LINQ (language integrated query) introduces extension methods. Example:We use the Average extension method to average all the elements in an int array. Tip:The Average method is implemented as an extension method within the .NET Framework. Extension Method Based on: .NET 4.5 Program that uses LINQ extension: C# using System; using System.Linq; class Program { static void Main() { int[] array = { 1, 3, 5, 7 }; Console.WriteLine(array.Average()); } } Output 4 Convert ToArrayToDictionaryToListToLookup Mutate Skip, SkipWhileTake, TakeWhile Computation Max, Min Var.
Download LINQPad. LINQ (Language-Integrated Query) LINQ to DataSet. LINQ to DataSet makes it easier and faster to query over data cached in a DataSet object. Specifically, LINQ to DataSet simplifies querying by enabling developers to write queries from the programming language itself, instead of by using a separate query language. This is especially useful for Visual Studio developers, who can now take advantage of the compile-time syntax checking, static typing, and IntelliSense support provided by the Visual Studio in their queries.
LINQ to DataSet can also be used to query over data that has been consolidated from one or more data sources. This enables many scenarios that require flexibility in how data is represented and handled, such as querying locally aggregated data and middle-tier caching in Web applications. In particular, generic reporting, analysis, and business intelligence applications require this method of manipulation. In This Section Getting Started Programming Guide Reference DataTableExtensions DataRowExtensions DataRowComparer See also.
Querying DataSets – Introduction to LINQ to DataSet - ADO.NET team blog. Greetings fellow data junkies! My name is Erick Thompson, a PM at Microsoft who is working on driving ADO.NET forward to utilize the latest and best technology that we have coming down the pipe. In that context, I am excited to tell you about LINQ to DataSet, a new and powerful way to write queries against the DataSet. The DataSet is a very useful in-memory representation of data, and acts as the core of a wide variety of data based applications. When the DataSet is loaded with data, it is usually by way of a DataAdapter. The DataAdapter generally restricts the data that is loaded into the DataSet, as it is rarely practical for an entire database to be loaded into a single instance of a DataSet.
Once the data is loaded, there is often a need to perform additional queries on the data. Select, RowFilter and Find The existing methods that can be used to write queries against the DataSet all utilize string based expressions, which have a SQL like syntax. Query Expression and Method Query. How to: Create DataRelations with the Dataset Designer. Relationships between data tables use DataRelation objects to connect records that are associated with each other, such as a customer and their orders. When you create data tables with the data design tools in Visual Studio, relationships are created automatically if the information can be gathered from the source of your data.
If you manually add data tables from the DataSet tab of the Toolbox, you may have to create the relationship manually as explained on this Help page. For information on creating DataRelation objects programmatically, see Adding DataRelations. Relationships between DataTables appear as lines on the Dataset Designer with a key and infinity glyph depicting the one-to-many aspect of the relationship. By default the name of the relationship does not appear on the design surface. To create a relationship between two DataTables Open your dataset in the Dataset Designer.
To toggle the display of relation names in the Dataset Designer. Introducing LINQ to Relational Data. Introducing LINQ to Relational Data With the combined launch of Visual Studio 2008, SQL Server 2008, and Windows Server 2008, Microsoft is introducing five implementations of .NET Language Integrated Query (LINQ). Of these five implementations, two specifically target access to relational databases: LINQ to SQL and LINQ to Entities.
This white paper introduces these two technologies and the scenarios in which each can best be used. Microsoft Language Integrated Query (LINQ) offers developers a new way to query data using strongly-typed queries and strongly-typed results, common across a number of disparate data types including relational databases, .NET objects, and XML. LINQ to SQL, released with the Visual Studio 2008, is designed to provide strongly-typed LINQ access for rapidly developed applications across the Microsoft SQL Server family of databases. What Is LINQ to SQL? Figures 1 & 2 combined with the code snippet below demonstrate a simple LINQ to SQL scenario. Figure 1. Figure 2. Walkthrough: Writing Queries in C# (LINQ)
This walkthrough demonstrates the C# language features that are used to write LINQ query expressions. After completing this walkthrough you will be ready to move on to the samples and documentation for the specific LINQ provider you are interested in, such as LINQ to SQL, LINQ to DataSets, or LINQ to XML. To create a project Start Visual Studio. On the menu bar, choose File, New, Project. The New Project dialog box opens. Expand Installed, expand Templates, expand Visual C#, and then choose Console Application. In the Name text box, enter a different name or accept the default name, and then choose the OK button. The data source for the queries is a simple list of Student objects. The Student class consists of auto-implemented properties. This whole data structure will be initialized and instantiated without explicit calls to any constructor or explicit member access. To add the data source To add a new Student to the Students list To create a simple query To execute the query Tasks.
LINQ: .NET Language Integrated Query. MSDN Library Articles and Overviews .NET General LINQ: .NET Language Integrated Query LINQ to SQL: .NET Language-Integrated Query for Relational Data .NET Language-Integrated Query for XML Data The .NET Standard Query Operators Overview of C# 3.0 534 out of 701 rated this helpful - Rate this topic LINQ: .NET Language-Integrated Query Don Box, Anders Hejlsberg February 2007 Applies to: Visual Studio Code Name "Orcas" .Net Framework 3.5 Summary: General-purpose query facilities added to the .NET Framework apply to all sources of information, not just relational or XML data.
Contents .NET Language-Integrated Query Getting Started with Standard Query Operators Language Features Supporting the LINQ Project More Standard Query Operators Query Syntax LINQ to SQL: SQL Integration LINQ to XML: XML Integration Summary .NET Language-Integrated Query After two decades, the industry has reached a stable point in the evolution of object-oriented (OO) programming technologies. Lambda Expressions and Expression Trees. LINQ to Objects - 5 Minute Overview. I want feedback on this article. Please leave your comments in the discussion page (click on the Discuss button on the top-right of this page) (See also: Main LINQ to Objects Page) LINQ to Objects Using C# 4.0: Using and Extending LINQ to Objects and Parallel LINQ (PLINQ) - This is my book, and much of the material initially came from this website and article.
Order on the Informit website or Amazon. LINQ to Objects allows .NET developers to write “queries” over collections of objects. Out of the box there is a large set of query operators that provide a similar depth of functionality to what we expect from any SQL language working with a relational database, and if what we need isn’t present out-of-the-box, we can add our own. Traditionally, working with collections of objects meant writing a lot of looping code using for loops or foreach loops to iterate through a list carrying out filtering using if statements, and some action like keeping a running sum of a total property. Output: 27. Understanding LINQ to Objects (2) Method Chaining - Dixin's Blog. [LINQ via C# series] It is obvious the Where(), OrderBy(), Select() can be invoked fluently: int[] source = new int[] { 0, 1, -2, 3, 24, 6, 3 }; var results = source.Where(item => item > 0 && item < 10) .OrderBy(item => item) .Select(item => item.ToString(CultureInfo.InvariantCulture)); This is called method chaining: after invoking one method, another method can be invoked immediately on the return value.
The following code cause the same results: var results = source.Where(item => item > 0) .Where(item => item < 10) .Select(item => item.ToString(CultureInfo.InvariantCulture)) .OrderBy(item => item); Method chaining is implemented by fluent interface. To implement a class with several behaviors, this normal design can be figured out in one second: The usage is also normal: There is nothing special. If making the IOtaku interface more fluent, the method invocations can be a chain. Here is the usage: The fluent IOtaku interface makes the programming more fluent.
The usage remains the same: LINQ Tutorial. LINQ via C# - Dixin's Blog. Dixin's Blog Dixin is a UI designer and knows a little bit about programming. Sign in | Join Home Contact Atom Comments RSS Search Tags Coding Guidelines Covariance And Contravariance Dynamic File System Functional Programming Hardware Haskell JavaScript jQuery LINQ to Objects LINQ to SQL LINQ via C# Series MacOSX Microsoft Microsoft Redmond Campus Office Profiling Ruby Seattle Silverlight SQL Server Testing UI Design Usability Visual Studio Web WebOS Windows Windows Media Center Sponsors advertise here News Microsoft Most Valuable Professional With Scott Hanselman , Principle Program Manager Lead of ASP.NET With Scott Guthrie , Father of ASP.NET Visitors since March 31st, 2010: Navigation Blogs Archives March 2012 (1) June 2011 (1) January 2011 (4) December 2010 (1) October 2010 (2) June 2010 (3) May 2010 (3) April 2010 (12) March 2010 (12) January 2010 (1) December 2009 (3) November 2009 (10) October 2009 (13) September 2009 (12) August 2009 (5) June 2009 (1) March 2009 (2) February 2009 (2) December 2008 (1) Friends Pages.
The World According to LINQ. Erik Meijer editor's note: This article uses many mathematical symbols that may not render propery in your browser. If the symbols do not display, you may wish to read the article in PDF format Programmers building Web- and cloud-based applications wire together data from many different sources such as sensors, social networks, user interfaces, spreadsheets, and stock tickers. Most of this data does not fit in the closed and clean world of traditional relational databases. It is too big, unstructured, denormalized, and streaming in realtime. Presenting a unified programming model across all these disparate data models and query languages seems impossible at first. Mathematicians long ago observed similarities between seemingly different mathematical structures and formalized this insight via category theory, specifically the notion of monads9 as a generalization of collections.
Take, for example, Apache's Hadoop5 ecosystem. Standard Query Operators and LINQ Datacentric Interpretation. LINQ and Productivity. Reactive Extensions. About the Reactive Extensions Whether you are authoring a traditional desktop or web-based application, you have to deal with asynchronous and event-based programming from time to time. Desktop applications have I/O operations and computationally expensive tasks that might take a long time to complete and potentially block other active threads. Furthermore, handling exceptions, cancellation, and synchronization is difficult and error-prone. Using Rx, you can represent multiple asynchronous data streams (that come from diverse sources, e.g., stock quote, tweets, computer events, web service requests, etc.), and subscribe to the event stream using the IObserver<T> interface. The IObservable<T> interface notifies the subscribed IObserver<T> interface whenever an event occurs. Extension Method.