Caution

This documentation is for EF Core. For EF6.x and earlier release see http://msdn.com/data/ef.

Basic Save

Learn how to add, modify, and remove data using your context and entity classes.

In this article:

Tip

You can view this article’s sample on GitHub.

ChangeTracker & SaveChanges

Each context instance has a ChangeTracker that is responsible for keeping track of changes that need to be written to the database. As you make changes to instances of your entity classes, these changes are recorded in the ChangeTracker and then written to the database when you call SaveChanges.

Adding Data

Use the DbSet.Add method to add new instances of your entity classes. The data will be inserted in the database when you call SaveChanges.

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            using (var db = new BloggingContext())
            {
                var blog = new Blog { Url = "http://sample.com" };
                db.Blogs.Add(blog);
                db.SaveChanges();

                Console.WriteLine(blog.BlogId + ": " +  blog.Url);
            }

Updating Data

EF will automatically detect changes made to an existing entity that is tracked by the context. This includes entities that you load/query from the database, and entities that were previously added and saved to the database.

Simply modify the values assigned to properties and then call SaveChanges.

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            using (var db = new BloggingContext())
            {
                var blog = db.Blogs.First();
                blog.Url = "http://sample.com/blog";
                db.SaveChanges();
            }

Deleting Data

Use the DbSet.Remove method to delete instances of you entity classes.

If the entity already exists in the database, it will be deleted during SaveChanges. If the entity has not yet been saved to the database (i.e. it is tracked as added) then it will be removed from the context and will no longer be inserted when SaveChanges is called.

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            using (var db = new BloggingContext())
            {
                var blog = db.Blogs.First();
                db.Blogs.Remove(blog);
                db.SaveChanges();
            }

Multiple Operations in a single SaveChanges

You can combine multiple Add/Update/Remove operations into a single call to SaveChanges.

Note

For most database providers, SaveChanges is transactional. This means all the operations will either succeed or fail and the operations will never be left partially applied.

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            using (var db = new BloggingContext())
            {
                db.Blogs.Add(new Blog { Url = "http://sample.com/blog_one" });
                db.Blogs.Add(new Blog { Url = "http://sample.com/blog_two" });

                var firstBlog = db.Blogs.First();
                firstBlog.Url = "";

                var lastBlog = db.Blogs.Last();
                db.Blogs.Remove(lastBlog);

                db.SaveChanges();
            }