Xamarin表单：更新应用程序时如何更新用户数据库

Question

I am using Sqlite.Net to save data when working on the Xamarin form. I am struggling how to update the tables if I added a new columns to an existing tables. At the moment, we are required to have the application to reinstall so user will have an updated database unless there is no changes to the database.

Answer 1

Probably you should maintain database versions. You can use something like

    Int32 current_version = 0;
    //increment this when you publish the version containing database changes
    Int32 latest_version = 5; 
    cmd.CommandText = "pragma user_version";
    current_version = (Int32) cmd.ExecuteScalar();
    if(current_version < latest_version) {
       // use alter table statements to add the new columns
    }

...

// finally stamp your database as having the latest version
cmd.ExecuteNonQuery("pragma user_version=" + latest_version);