LINQ

Acknowledging that some algorithms cannot be naturally expressed in LINQ, there will also be a set of imperative data parallel APIs.

After you add a LINQ to SQL file to your project, the empty design surface represents a DataContext ready to be configured.

I promised there would be a little Linq code in this application, so I'm going to use Linq to generate a report for me.

Well, the Linq architecture revolves around the concept of delayed execution.

When you want to use Language-Integrated Query (LINQ) to access data in a database, you do not connect directly to the database.

In LINQ to SQL, the data model of a relational database is mapped to an object model expressed in the programming language of the developer.

Explains the behavior you can expect to see if you try to edit LINQ code while you are debugging.

This section contains basic background information that will help you understand the rest of the LINQ documentation and samples.

Still, Astoria will support other non-database, like LINQ-enabled data sources to be exposed through the HTTP interface.

Once you set it up, which requires studying the "readme" file very carefully, using LINQ to XSD is quite easy.

As a rule when you write LINQ queries, we recommend that you use query syntax whenever possible and method syntax whenever necessary.

Currently LINQ to XSD is only available as source code, no binaries have been published.

As described in Query Syntax versus Method Syntax ( LINQ ) , some query operations can only be expressed by using method syntax .

The Query Across Relationships walkthrough demonstrates how LINQ to SQL can query across tables, similar to joins in a relational database.

For a developer who writes queries, the most visible "language-integrated" part of LINQ is the query expression.

Parallel LINQ, part of Microsoft's Parallel Extensions library, allows developers to quickly make queries execute across multiple threads.

It provides the in-memory document modification capabilities of the Document Object Model (DOM), and supports LINQ query expressions.

LINQ technology is a form of declarative, functional programming.

You will also produce a log output to show the SQL commands that LINQ to SQL generates.

Describes the three parts of the basic LINQ query operation that are common across all languages and data sources.

When the database returns the results, LINQ to SQL translates them back to objects that you can work with in your own programming language.

LINQ closes the gap between the programming world and the data world by providing a common query facility for in-memory and external data.

When a LINQ expression directly targets a database, the DLINQ provider has full access to the database's indexes.

Language-integrated query (LINQ) support provides compile-time syntax validation for queries against a conceptual model.

For more information, see Responsibilities of the Developer In Overriding Default Behavior (LINQ to SQL).

Describes tools available in the Visual Studio environment for designing, coding, and debugging LINQ-enabled application.

Formulating queries using LINQ to DataSet is similar to using Language-Integrated Query (LINQ) against other LINQ-enabled data sources.

You cannot change, add, or remove a LINQ query, however, unless you want to stop debugging to apply the changes.

A: LINQ to SQL does not support mixing and matching entities loaded from different DataContext instances together in the same object graph.

You can add or remove code before the LINQ statement, even if the changes affect the line number of the LINQ query.

Binding has interesting applicability especially when LINQ expressions are involved.

External mapping in LINQ to SQL must be valid against the following XML schema definition.

When serializing, LINQ to XML attempts to serialize with the namespace prefix specified in namespace attributes.

Note that the second execution of the compiled LINQ query is equivalent to the second execution of the Entity SQL query.

In the LINQ approach, you write declarative code that describes what you want to retrieve.

However, before completely rewriting an algorithm, consider the parallel extensions for LINQ.

This topic contains links to Language-Integrated Query (LINQ) programming walkthroughs.

The following example shows a typical LINQ query, followed by the translation of the query into method format.

The headline feature of this release is LINQ (Language Integrated Query).

Describes the. NET Framework version, namespaces and references required to create LINQ projects.

For this purpose, the DLR has extended LINQ expression trees to include control flow, assignment, and other language-modeling nodes.

LINQ to SQL does not support the hybrid use of the two mapping approaches (attribute-based and external).

The plan is to reimplement the whole of LINQ to Objects, explaining each method (or group of methods) in a blog post.

I will write up a blog entry for each LINQ operator, probably including all of the production code but only "interesting" tests.

Another idea LINQ borrows, this time from dynamic languages, is the idea of "extension methods" .

Shows how to bind the results of a LINQ query to a control on a Windows Form.

After you add the new LINQ to SQL file to the project, the empty design surface opens, displaying two separate panes.

The implementation strategy for LinQ involves rewriting the query into API calls against a provider.

This. NET Framework version includes support for ASP. NET AJAX and Language-Integrated Query (LINQ).

In the context of LINQ to SQL, the DataContext methods that map to stored procedures are the same as those that map to functions.

Memory consumption on analyzing large files has been greatly reduced, which should benefit ASP. NET and LINQ to SQL developers.

Click the LINQ to SQL Classes template and type Northwind. Dbml in the Name box.

To simplify the LINQ to XML programming interface, namespaces are represented in the XML tree as attributes.

Provides an example of how to return the results of a LINQ query as a specific type instead of as an anonymous type.

LINQ to SQL checks those values against the database before it updates or deletes the data.

This walkthrough provides a fundamental end-to-end LINQ to SQL scenario with minimal complexities.

Links to a sample that demonstrates how LINQ uses reflection.

This example is intended to demonstrate usage, and might not run faster than the equivalent sequential LINQ to Objects query.

However, functional transformation has a much wider applicability than use with LINQ.

In this first task, you create a Visual Studio solution that contains the necessary references to build and run a LINQ to SQL project.

In addition to working directly with the node tree, developers will also have access to a LINQ provider.

LINQ applies the principles of object-oriented programming to relational data.

Then one can iterate over the data with LINQ, and process it accordingly.

If your application generates a run-time error, see the Troubleshooting section of Learning by Walkthroughs (LINQ to SQL).

In a basic sense, LINQ to Objects represents a new approach to collections.

In this section, you will add controls to the page that use the LINQ to SQL Classes file that mapped the database table to classes.

Closures, and the related concept lambda expressions, are used throughout the LINQ query design.

When these properties are true, the LinqDataSource control uses LINQ to SQL to automatically create the commands to modify the data.

LinQ enables developers to embed object-valued queries directly in their code.

Provides links to topics that explain LINQ and provide examples of code that perform queries.

Explains stepping behavior during LINQ debugging.

Run the project, and select the type of LINQ sample that you want to explore.

This makes the object layer an ideal target for Language-Integrated Query (LINQ) support.

These features are combined in LINQ, which we will use to query data throughout this book.

Edit and Continue does not support changes to LINQ queries.

Describes special circumstances to consider when you view LINQ query results in the debugger.

LINQ to SQL detects that an entity belongs to another DataContext if any deferred properties are still unloaded.

LINQ depends largely on the language features that were introduced and also on bits of the Fx 3. 5 (4 assemblies to be precise).

Discusses techniques for debugging LINQ queries.

Includes an overview of queries in LINQ and provides links to additional resources.

Like other objects, LINQ to SQL classes can use inheritance and be derived from other classes.

This topic gives a brief introduction to LINQ query expressions and some of the typical kinds of operations that you perform in a query.

Provides a brief overview of LINQ to XML and provides links to the LINQ to XML documentation.

Participate in the LINQ Forum, where you can discuss more complex topics in detail with experts.

Construct a simple LINQ query and display the results on the form.

By default, the logic to perform updates is provided by the LINQ to SQL runtime.

LinQ also requires support for lambda expressions (closures), though this is not obvious from the previous query example.

In addition to the steps for displaying the data from the table, the steps for binding data to a LINQ query are also provided.

The following examples demonstrate some simple LINQ queries by using each approach listed previously.

In LINQ the join clause always works against object collections instead of database tables directly.

You can use LINQ queries in new projects, or alongside non-LINQ queries in existing projects.

There is no way the ADO. NET Team can do what is right for LINQ To SQL given their obvious bias to the Entity Framework.

Not surprisingly, the same is true for Language Integrated Query (LINQ).

LINQ is composable, but at a certain point, it just becomes easier to simply build a string.

Next, we call the target method and then use the LINQ Zip method to ensure that every price has changed.

With LINQ, a query is now a first-class language construct, just like classes, methods, events and so on.

XML Literals, Members, and Namespaces, which along with LINQ are the crown jewels of VB 9, will be supported.

This becomes extremely useful when writing LINQ queries.

First up is a no-brainer, updating LINQ to SQL diagrams when the underlying database changes.

Under Visual Studio installed templates, select LINQ to SQL Classes, rename the file to Tasks. Dbml, and then click Add.

The Microsoft. NET Framework includes three models for processing XML data: the XmlDocument class, the XPathDocument class, and LINQ to XML.

Provides links to topics that explain the LINQ technologies.

Construct various LINQ queries to return filtered data.

Using the LinqDataSource control to connect to a database by using Language-Integrated Query (LINQ).

In C#, you cannot use Edit and Continue on any code in a method that contains a LINQ query.

You can use LINQ query syntax to expressively indicate how to query your data model in a strongly typed way.

Compares method syntax and query syntax as two ways to express a LINQ query.

Provides a brief introduction to generic types as they are used in LINQ.

Shows how to use regular expressions in LINQ queries for complex pattern matching on filtered query results.

A better outcome would have seen MS announce a successor to both LINQ To SQL and Entity Framework.

You add LINQ to SQL files to projects by using the Add New Item dialog box and selecting the LINQ to SQL Classes template.

Add. Dbml files to projects by selecting the LINQ to SQL Classes template in the Add New Item dialog box.

For more information, see Edit and Continue With LINQ.

Read about the "from clause" in the next section to learn about the order of clauses in LINQ query expressions.

To use LINQ to SQL effectively, you must have some familiarity with the underlying principles of relational databases.

For more information, see Introduction to LINQ Queries.

In this post I'm going to outline what steps are involved to get LINQ working based on what providers you may want to use.

Entity classes are created and stored in LINQ to SQL Classes files (. Dbml files).

Before you can begin querying a DataSet object using LINQ to DataSet, you must populate the DataSet.

The DBML Extractor is a LINQ to SQL component that takes database metadata as input and produces a DBML file as output.

To use this file correctly for validating an external mapping file, see How to: Validate DBML and External Mapping Files (LINQ to SQL).

LINQ simplifies this situation by offering a consistent model for working with data across various kinds of data sources and formats.

In addition, Edit and Continue does not support changing the type or the value of a variable that is used in a LINQ statement.

In this video, LINQ is used to query relational databases.

Provides reference information about several aspects of LINQ to SQL.

Designer then takes care of creating mapping and generating proper LINQ To SQL code.

Provides a condensed overview of LINQ to SQL along with information about how to get started using LINQ to SQL.

LINQ is something that is actually integrated into the programming language itself.

The join methods provided in the LINQ framework are Join and GroupJoin.

Add a LINQ to SQL file to a project.

This is one benefit of the strong type-checking provided by LINQ.

At the same time in terms of security, the use of LINQ itself is a clever solution to the problem of SQL injection attacks.

Add code to run a LINQ query.

Perst 3. 0 offers full text search, compressed objects under Java, and LINQ support under . NET.

LINQ to DataSet can also be used to query over data that has been consolidated from one or more data sources.

Complexpointcuts, for instance, could be expressed as a language-integrated query (LINQ) in C# 3. 0.

The execution time for the compiled LINQ query is 305 ms on the first execution and 15 ms on subsequent ones.

There are several ways to load data into a DataSet, such as using the DataAdapter class or LINQ to SQL.

Ask questions about the LINQ Project.

The result is a LINQ to SQL entity class that maps to the table in the database.

The problem is actually how to get the SQL generated by LINQ queries to use the NOLOCK hint as SQL developers are accustomed.

It provides strongly-typed LINQ data access experience over relational databases, including direct, efficient access to SQL Server.

For more information about how to create LINQ queries, see Introduction to LINQ Queries.

Discusses the use of expression trees in LINQ.

In this video, LINQ is used to query XML files.

LINQ to XML is the new model in the. NET Framework version 3. 5 For processing XML data.

For more information, see How to: Validate DBML and External Mapping Files (LINQ to SQL).

Provides an example of how to order the results of a query by using LINQ.

To use the XSD file correctly for validating a DBML file, see How to: Validate DBML and External Mapping Files (LINQ to SQL).

As we said, we are big fans of LINQ, and it plays an important role in MVC applications.

XML data can as easily be parsed and consumed with LINQ to XML, which is part of . NET Framework 3. 5.

Provides an example of how to include search criteria in a query by using LINQ.

Object representations of data, such as LINQ to SQL entity classes.

At that time it was a LINQ provider that could automatically parallelize queries.

For example, the LINQ system in Microsoft's . NET is a direct descendent of functional programming techniques.

When . NET 4. 0 was released the most common scenario was fork-join style programming such as seen with Parallel. ForEach and Parallel LINQ.

Describes how to query data that is defined by a conceptual model by using LINQ and stored procedures.

But LINQ is not only about databases, it can also target XML or even simple object collections.

In order to upgrade your apps to use new features like LINQ you'll need to change the target framework and add some references.

Create controls that are bound to entity classes by dragging LINQ to SQL data source items from the Data Sources window onto a Windows Form.

In Visual Basic, you can use Edit and Continue on non-LINQ code, even in a method that contains a LINQ query.

Visual Basic provides XML axis properties for accessing and navigating LINQ to XML structures.

For more information about query execution, see Writing Your First LINQ Query (Visual Basic).

The following example uses an in-memory data structure as the data source, but the same principles apply for any kind of LINQ data source.

Open the LINQ to SQL file in the designer.

Step-by-step instructions for creating a C# LINQ project, adding a simple data source, and performing some basic query operations.

Provides links to sections that describe how to use LINQ to XML in Visual Basic.

Improvements to LINQ queries: additional canonical functions and automatic mapping from CLR functions to server functions

Below are the first five parts of my LINQ to SQL series

Below are the first two parts of my LINQ to SQL series

"Linq-friendly" annotation capabilities, to allow developers to use the SDK with emerging Linq to XML technology

Then read the documentation for the LINQ technology in which you are interested

The following code sample taken from the SDK's help file shows the usage of LINQ's chained where clause in the context of accessing YouTube

Using LINQ to XSD, the query is written in a much clearer and type-safe way

Type Relationships in Query Operations (LINQ)

Follow these steps to find additional examples of LINQ to SQL code and applications

Adding LINQ to SQL Data Classes to a Project

In addition, LINQ queries offer three main advantages over traditional foreach loops

a rich programming experience using Entity SQL and LINQ

Better support for span over LINQ to Entities queries

In my first post I provided code samples that demonstrated how to perform common data scenarios using LINQ to SQL including

How to: Generate the Object Model as an External File (LINQ to SQL)

XMLQuerying Collection and XML with LINQ

For example, consider the below LINQ to SQL example

Walkthrough: Simple Object Model and Query (Visual Basic) (LINQ to SQL)