In my previous post I talked about general usage of SQL CE database in Mango.  In this example I am going to talk about keeping the database schema updated.

For example, I want to add a column to Person table from previous post.  I would like to add Notes column with the following definition:

        [Column(DbType = "NVarChar(300) NULL")]

        public string Notes { get; set; }

Now I am going to use DatabaseSchemaUpdater class to accomplish this.  First of all, I have to add using statement to my program in order to invoke extension method on my data context:

using Microsoft.Phone.Data.Linq;

Now, I am going to add some code after the database exists check and add the column as follows:

                DatabaseSchemaUpdater db = App.CurrentApp.DB.CreateDatabaseSchemaUpdater();

                if (db.DatabaseSchemaVersion == 0)

                {

                    db.AddColumn<Person>("Notes");

                    db.DatabaseSchemaVersion = 1;

                    db.Execute();

                }

Here is what I am doing here.  I am checking for DB version, which I am going to assume responsibility for updating from now on.  I am adding notes column called Notes to Person table.  Then I am bumping version number for subsequent updates.  Lastly, I am firing Execute method to commit my changes.  Pretty easy all-and-all.  I only wish that Entity Framework code first had similar functionality.