Subsonic and optimistic concurrency

Question

Does Subsonic use optimistic concurrency?

Answer 1

If using use , you mean built-in for SubSonic, then no. However, optimistic concurrency can be achieved with SubSonic quite simply.

Assuming you are using SQL Server (if not, I will let you translate the following instructions into a solution that works with your database provider), this is one way:

• Include a type column timestampin each table that you want to provide concurrency.

  CREATE TABLE Product
  (
      ProductID int NOT NULL IDENTITY(1,1),
      Name varchar(256) NOT NULL,
      RowStamp timestamp  /* This will hold a timestamp for the table */
  )
  

• Read the value of the timestamp along with the data to use it later for comparison.

  var product = new SubSonic.Select()
      .From<Product>()
      .Where(Product.ProductIDColumn).IsEqualTo(productId)
      .ExecuteSingle<Product>();
  var rowStamp = product.RowStamp;
  
  // ...  Show a form to the user with the data from the product      
  

• UPDATE . , , ( , )

  // ... After retrieving the values from the form
  
  var result = new SubSonic.Update(Product.TableSchema)
      .Set(Product.NameColumn).Equal(newName)
      .Where(Product.ProductIDColumn).IsEqualTo(productId)
      .And(Product.RowStamp).IsEqualTo(rowStamp)
      .Execute();
  
  if (result != 1)
  {
      // Notify the user there may be a problem
  }
  

Answer 2

, .

http://sites.google.com/site/subsonicoptimistic/home