An error occurred while updating the entries savechanges

Select a department from the drop-down list and click Filter: This time the first breakpoint will be for the departments query for the drop-down list.

Skip that and view the SELECT [Project1].[Course ID] AS [Course ID], [Project1].[Title] AS [Title], [Project1].[Credits] AS [Credits], [Project1].[Department ID] AS [Department ID], [Project1].[Department ID1] AS [Department ID1], [Project1].[Name] AS [Name], [Project1].[Budget] AS [Budget], [Project1].[Start Date] AS [Start Date], [Project1].[Instructor ID] AS [Instructor ID], [Project1].[Row Version] AS [Row Version] FROM ( SELECT [Extent1].[Course ID] AS [Course ID], [Extent1].[Title] AS [Title], [Extent1].[Credits] AS [Credits], [Extent1].[Department ID] AS [Department ID], [Extent2].[Department ID] AS [Department ID1], [Extent2].[Name] AS [Name], [Extent2].[Budget] AS [Budget], [Extent2].[Start Date] AS [Start Date], [Extent2].[Instructor ID] AS [Instructor ID], [Extent2].[Row Version] AS [Row Version] FROM [dbo].[Course] AS [Extent1] INNER JOIN [dbo].[Department] AS [Extent2] ON [Extent1].[Department ID] = [Extent2].[Department ID] WHERE @p__linq__0 IS NULL OR [Extent1].[Department ID] = @p__linq__1 ) AS [Project1] ORDER BY [Project1].[Course ID] ASC line.

One way to do that is to use parameterized queries to make sure that strings submitted by a web page can't be interpreted as SQL commands.

You'll sort the courses by title, and you'll specify eager loading for the With the breakpoint still set, run the Course Index page.

Continue through the first times that the code hits a breakpoint, so that the page is displayed in the browser.

Implementing these patterns can help insulate your application from changes in the data store and can facilitate automated unit testing or test-driven development (TDD).

However, writing additional code to implement these patterns is not always the best choice for applications that use EF, for several reasons: For more information about how to implement the repository and unit of work patterns, see the Entity Framework 5 version of this tutorial series.

But there are exceptional scenarios when you need to run specific SQL queries that you have manually created, and these methods make it possible for you to handle such exceptions.

As is always true when you execute SQL commands in a web application, you must take precautions to protect your site against SQL injection attacks.

Many developers write code to implement the repository and unit of work patterns as a wrapper around code that works with the Entity Framework.

These patterns are intended to create an abstraction layer between the data access layer and the business logic layer of an application.

The data in memory acts as a cache and is used when you update an entity.

This caching is often unnecessary in a web application because context instances are typically short-lived (a new one is created and disposed for each request) and the context that reads an entity is typically disposed before that entity is used again.

In Click the magnifying class to see the query in the Text Visualizer.