Entity Framework Transaction Learn How it Works with SaveChanges

In Entity Framework, when you call SaveChanges() to insert, delete, or update data to the database, the entity framework will wrap that operation in a transaction.

The transaction allows several database operations to be processed atomically.
If it is committed, all of the operations are successfully applied to the database.
If the transaction is rolled back, none of the operations are applied to the database.

Default Behaviour

In Entity Framework, SaveChanges automatically starts a transaction and commits or rolls it back.
It means the Entity Framework maintains a transaction for the multiple entity inserts, update and delete in a single SaveChanges() method.
When we execute another operation, the Entity Framework creates a new transaction.

The following example saves two author entities by calling SaveChanges() for each entity.

using (var context = new BookStore())
{
    context.Database.Log = Console.WriteLine;
    Author author1 = new Author() {    Name = "Mark" };
    Author author2 = new Author() {    Name = "John" };
        
    context.Authors.Add(author1);
    context.SaveChanges();
    
    context.Authors.Add(author2);
    context.SaveChanges();
}

You can see that EF saves both entities in separate transactions.

Opened connection at 10/29/2018 9:18:26 AM +00:00
Started transaction at 10/29/2018 9:18:26 AM +00:00

INSERT [dbo].[Authors]([Name])
VALUES (@0)
SELECT [AuthorId]
FROM [dbo].[Authors]
WHERE @@ROWCOUNT > 0 AND [AuthorId] = scope_identity()

-- @0: 'Mark' (Type = String, Size = -1)
-- Executing at 10/29/2018 9:18:26 AM +00:00
-- Completed in 3 ms with result: SqlDataReader

Committed transaction at 10/29/2018 9:18:26 AM +00:00
Closed connection at 10/29/2018 9:18:26 AM +00:00

Opened connection at 10/29/2018 9:18:26 AM +00:00
Started transaction at 10/29/2018 9:18:26 AM +00:00

INSERT [dbo].[Authors]([Name])
VALUES (@0)
SELECT [AuthorId]
FROM [dbo].[Authors]
WHERE @@ROWCOUNT > 0 AND [AuthorId] = scope_identity()

-- @0: 'John' (Type = String, Size = -1)
-- Executing at 10/29/2018 9:18:26 AM +00:00
-- Completed in 1 ms with result: SqlDataReader

Committed transaction at 10/29/2018 9:18:26 AM +00:00
Closed connection at 10/29/2018 9:18:26 AM +00:00

Try it

Multiple Operations in Single Transaction

You can use multiple SaveChanges within a single transaction as shown below;

using (var context = new BookStore())
{
    context.Database.Log = Console.WriteLine;
    using (DbContextTransaction transaction = context.Database.BeginTransaction())
    {
        try
        {
            Author author1 = new Author() {    Name = "Mark" };
            Author author2 = new Author() {    Name = "John" };
            
            context.Authors.Add(author1);
            context.SaveChanges();
            
            context.Authors.Add(author2);
            context.SaveChanges();
            transaction.Commit();
        }
        catch (Exception ex)
        {
            transaction.Rollback();
        }
    }
}

You can see that both author entities are saved to the database in one transaction.

Opened connection at 10/29/2018 9:21:20 AM +00:00
Started transaction at 10/29/2018 9:21:20 AM +00:00

INSERT [dbo].[Authors]([Name])
VALUES (@0)
SELECT [AuthorId]
FROM [dbo].[Authors]
WHERE @@ROWCOUNT > 0 AND [AuthorId] = scope_identity()

-- @0: 'Mark' (Type = String, Size = -1)
-- Executing at 10/29/2018 9:21:20 AM +00:00
-- Completed in 3 ms with result: SqlDataReader

INSERT [dbo].[Authors]([Name])
VALUES (@0)
SELECT [AuthorId]
FROM [dbo].[Authors]
WHERE @@ROWCOUNT > 0 AND [AuthorId] = scope_identity()

-- @0: 'John' (Type = String, Size = -1)
-- Executing at 10/29/2018 9:21:20 AM +00:00
-- Completed in 0 ms with result: SqlDataReader

Committed transaction at 10/29/2018 9:21:20 AM +00:00
Closed connection at 10/29/2018 9:21:20 AM +00:00