Updating data using linq to sql
Finally, we have chosen this feature for Q2 2013 with an important input from our Ideas & Feedback portal and previous requests.
Do not forget to provide your feedback on this or any other feature of the product - just post your ideas for improvements in the portal, so that the entire community can express interest in them!
As the number of out of stock products in the Products table grows, the number of SQL statements executed grows.
This demonstrates a very common problem with Entity Framework and other object-relational mapping libraries.
If it is your first MVC project then check the structure of application, Content (contains theme and css files), Controllers (contains our controller classes), Models (Models to use in view to pass values from page to controllers) and Views (page UI).
To keep this article simple, we will use LINQ To SQL Classes to fetch data from database, so create LINQ To SQL Class by right clicking on the solution New Item.., it will open a dialog to add new item so select LINQ To SQL Classes and give name Open Sever Explorer from view menu and add your database, where you created your products table, say Northwind Drag Products table to the surface Our application structure is completed, now we will create our own controller.
This is quite useful for most scenarios, as the typical data intensive application performs CRUD operations mostly based on user interaction, which means that the volume of the changes is usually not very large.
For instance: On the other hand, consider a scenario where a maintenance task, a deployment script or just some complex business logic requires changes to be applied not on one, two or three entities, but on ten thousand.
So in this article we will see how to select records from database (with Web Grid, pagination and sort functionality), update a record, add new record and finally delete a record in ASP. Let’s create a simple table Products with very basic columns for now, here is the table structure: CREATE TABLE [Products]( [Product Id] [int] IDENTITY(1,1) NOT NULL, [Product Name] [varchar](50) NOT NULL, [Price] [decimal](18, 2) NOT NULL, [Qunatity] [int] NOT NULL, [Reorder Level] [int] NOT NULL, CONSTRAINT [PK_Products_1] PRIMARY KEY CLUSTERED ( [Product Id] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] ) ON [PRIMARY] GO Internet Application View engine: Razor Don’t create a unit test project; it is out of scope of this article.
Net to open a database connection, create a command object, execute a SQL statement, iterate through the results and create your C# class instances (objects) manually. Updating individual records in Entity Framework is straightforward and relatively simple: create a context, load the record to be updated, update the properties, and save the changes.
The following method marks a single product as discontinued, based on the product ID: As you can see, I’m using a simple LINQ query to get a single product with a Product ID matching the product ID parameter of the method, setting the Discontinued flag, and saving the changes. Let’s say I wanted to discontinue all products which are out of stock and have no units on order, instead of just one.
call in order to be applied - they are executed instantaneously!
So be careful with the delete statements - powerful weapons should be handled with caution.
NET API, or the Open Access ADO API in your Data Layer, it is both error prone and backend-dependent.