Also, within the N-Layer architecture, you can guess that Entity Framework fits as the DAL Layer (Data Access Classes) as well as using EF entities as our disconnected entities to pass thru all the layers, all right?
BTW, not all N-Layer apps should be N-Tier apps, but all N-Tier Apps must internally be designed as N-Layer. , so if we get back to the N-Tier architecture (physical tiers), like I said, we need remote mechanisms to communicate the client tier with the application server tier (for instance, WCF Services) and therefore when we query the database from the app server tier, to obtain data (like an Order), we keep it as an EF entity, then we disconnect it from the EF context (detach), WCF serializes it and sends that disconnected entity to the presentation tier (client apps & machines).
Before doing this, you must first set all properties that do not support null (Nothing) values. Append the following block to the existing code and launch the project: C# To extract an instance from a context use the Delete On Submit method of the corresponding collection.
The Submit Changes() method generates and executes commands that perform the equivalent INSERT, UPDATE, or DELETE statements against the data source. Insert On Submit(new Product); // Send the changes to the database. The object is removed from the collection of its type, but not destroyed.
This tutorial guides you through the process of creating a simple application powered by Linq Connect technology.
In less than 5 minutes you will have a ready-to-use data access layer for your business objects.
Add the following block of code to the method Main: C# Crm Demo Data Context context = new Crm Demo Data Context(); var query = from it in context. Company ID select it; foreach (Company comp in query) Console. What earlier was adding rows to tables, now is just adding new objects to context collections. ' Until you do it, the changes are cached on the client side. Submit Changes() ' Request the new product from the database Dim query = From it In context.products _ Where it. Note that after you have added the new product and category by submitting the changes, you cannot execute this solution again as is.
When you are ready to send the changes to the database, call Submit Changes() method of the context. Product ID = 2000 _ Select it ' Since we query for a single object instead of a collection, we can use the method First() Dim product As product = query. To execute the solution again, change the IDs of the objects to be added. The only thing to remember is that you have to invoke the Submit Changes() method to send the data to the database.In this walkthrough: Linq Connect (formerly known as LINQ to SQLite) is the fast and lightweight ORM solution, which is closely compatible to Microsoft LINQ to SQL and contains its own advanced features, such as complex type support, advanced data fetching options, configurable compiled query caching, and others.LINQ stands for Language-Integrated Query, which means that data retrieval is no longer a separate language. NET applications to connect to databases without bothering much about columns and rows.The type-safe LINQ queries get compiled into MSIL on the fly, and the query clauses are translated into SQL and sent to SQLite database for execution.This makes your data access layer safer, faster, and greatly more convenient to design.In this tutorial it is assumed that you already have the database objects created.