Visual Data Components Visual Studio. NET components and data— bound controls to work in visual form. That means you can use these components as you use any windows controls. You drag and drop these components on windows and web forms set their properties and write events. It helps programmers to write less code and develop applications in no time. NET also offers the data form wizard, which you can use to write full-fledged database applications without writing a single line of code.
Performance and Scalability Performance and scalability are two major factors when developing web-based applications and services.
Transferring data one source to another is a costly affair over the Internet because of connection bandwidth limitations and rapidly increasing traffic. Using disconnected cached data in XML takes care of both of these problems. NET you use as few connections as possible and have more disconnected data. So there are performance problems with that.
However, ADO. In ADO. NET, you store data in a dataset and close the make final changes to the data source. You create a DataReader by calling Command. ExecuteReader after creating an instance of the Command object. Learn more about DataReader vs DataSet. NET Entity Framework is designed to enable developers to create data access applications by programming against a conceptual application model instead of programming directly against a relational storage schema.
The goal is to decrease the amount of code and maintenance required for data-oriented applications. For more information, see ADO.
NET Entity Framework. NET is designed to work with multiple kinds of data sources in same fashion. You can categorize ADO. NET components in three categories: disconnected, common or shared and the. NET data providers. The disconnected components build the basic ADO. NET architecture. You can use these components or classes with or without data providers. For example, you can use a DataTable object with or without providers and shared or common components are the base classes for data providers.
Shared or common components are the base classes for data providers and shared by all data providers. The data provider components are specifically designed to work with different kinds of data sources. Applications that reference this assembly may fail. For more information about improvements and features that were added to the Entity Framework 5.
Feedback will be sent to Microsoft: By pressing the submit button, your feedback will be used to improve Microsoft products and services. Privacy policy. Skip to main content. This browser is no longer supported. Download Microsoft Edge More info.
Contents Exit focus mode. The context menu with same behavior appears in Visual Studio with a different name, "Retrieve Data". The EnlistDistributedTransaction method of the data provider Connection object is obsolete.
You can use the EnlistTransaction method introduced in the. NET Framework 2. We recommend that you use System. Transaction for all transactions instead. They are replaced by the Encryption Method connection string option and EncryptionMethod property. I will not spend a lot of time focusing on the older style of building relationships in this book as it is not the default and will be used minimally. If you need in-depth guidance on how to work with relationships when the foreign key is not available in the conceptual model, I recommend that you read the first edition of this book.
As you will find, especially in Chapter 19 , which dives deep into relationships, even with foreign keys, you will need to have a very good understanding of how relationships work. Some of the rules of engagement when working with related data are not very intuitive, and you can write code that will raise plenty of exceptions, or worse, will return invalid results, if you break these rules.
Chapter 19 will provide insight into relationships in the EDM so that you will be able to work with them in an expert manner. You can use entities in many. NET data binding scenarios. In Windows Forms and WPF, you can use entities as a data source for data-bound controls or as the data source for BindingSource controls, which orchestrate the binding between objects and UI controls on the form.
Chapter 9 provides a well-informed walkthrough for using entities with BindingSource controls to edit and update data. Chapter 26 focuses on separating the data access and other business logic from the user interface to provide better architecture for your applications.
For ASP. Chapter 12 is all about using EntityDataSource. NET Dynamic Data in that chapter. Entity Framework made significant advancements for n -tier development in. NET 4. Now we can benefit greatly from not only the foreign keys but also a slew of state management methods that make working across processes much simpler. For layered applications, Chapter 24 and Chapter 25 focus on pulling all of the data access tasks out of the ASP. EntityClient is the other major API in the Entity Framework, though one that you are less likely to work with directly.
It provides the functionality necessary for working with the store queries and commands in conjunction with the database provider connecting to the database, executing the commands, retrieving the results from the store, and reshaping the results to match the EDM.
Not only is EntityClient able to perform queries, but it does this on behalf of Object Services. The difference is that when you work directly with EntityClient , you will get tabular results though the results can be shaped. If you are working with Object Services, it will transform the tabular data created by EntityClient into objects.
The tabular data returned by EntityClient is read-only. EntityClient is well suited for reporting and moving data from one persistence mechanism to another. Only Object Services provides change tracking and the ability to save changes back to the data store. NET stack. Can you continue to write new code using these technologies? DataSet s and DataReader s are not going away. All of your existing investment will continue to function and you can continue to use this methodology of retrieving data and interacting with it.
The Entity Framework provides a completely different way to retrieve and work with data. You would not integrate the two technologies—for example, using the Entity Framework to query some data, and then pushing it into a DataSet; there would be no point. You should use one or the other. As you learn about the Entity Framework, you will find that it provides a very different paradigm for accessing data.
You may find that the Entity Framework fits for some projects, but not others, where you may want to stick with DataSet s. This is what a query with EntityClient returns. It uses connections, commands, and command parameters, and returns a DbDataReader that you can read as you would any other DataReader , such as SqlDataReader.
Some ADO. Additionally, ADO. Therefore, when the Entity Framework saves changes to the database, it can send only one command at a time. They both provide LINQ querying against a database using a data model.
A frequently asked question is: why did Microsoft create two similar technologies? By the time each technology had come along far enough that it was being shown to other teams at Microsoft, it was clear that Microsoft had two great new technologies that could target different scenarios. NET and has made no statements regarding deprecating it. In the first edition of this book, Chapter 1 listed two pages of pain points.
NET 4 and Visual Studio There are still definitely a lot of nits to pick, however. The model would benefit from support for things such as unique foreign keys, table-valued functions, enhanced many-to-many relationships, and a problem that is much more than a nit: support for very large models.
Take a look at Chapter 19 for a good study guide. This book spends plenty of time looking into the depths of the Entity Framework runtime to show you how to get around some of these limitations, and attempts to point out potholes, hiccups, and omissions.
Users of more mature ORM tools continue to have complaints about Entity Framework as well, such as the difficulty of providing internal transactions database transactions, however, are supported.
As you read through this book, you will gain experience in designing EDMs and using the Entity Framework to write applications, as well as dig deep into the APIs to learn how to manipulate entity objects and have granular control over much of their behavior.
0コメント