Saving Data on Android

SQLiteOpenHelper
 implementation is created with a different version number in its 
constructor.
The implementation of this method should provide the code that is necessary to 
upgrade to the new version of the schema. Since this is a very simple example, you're 
just dropping the previous table, and recreating it, using the new schema. But in real 
environments, and big apps, you'd usually do something called a 
migration
.
Migration is the process of updating the database, without dropping it. For example, 
if you decide to add a new field to the TODO model, called 
toDoPriority
, you would 
need to change the database as well, because you need to store that field, and 
retrieve it, but the old database doesn't have that field defined. You would then 
update the version number (e.g., from 
1
 to 
2
) and write a SQL statement, to