Difficulty in upgrading SQlite table

Question

I have an application running with a working table called ANIMAL. Upon first creating this table it consisted simply of _id and animal_name columns.

Now I am trying

Answer 1

If you are using SQLiteOpenHelper it's easy to upgrade a table. You need to implement methods onCreate and onUpgrade and provide current version of your database in class constructor. When updating your table just increment database version number, specify new table creation query in onCreate method and put ALTER TABLE to onUpgrade method to update previous version of table. When Android detects database version mismatch, it will call onUpgrade method automatically. See the example:

public class OpenHelper extends SQLiteOpenHelper {

    private final static int    DB_VERSION = 2;

    public TracksDB(Context context) {
        super(context, DB_NAME, null, DB_VERSION);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        final String CREATE_TBL =
            "create table " + ANIMALS_TABLE +
            " (_id integer primary key autoincrement, " + 
            "animal_name text not null, " +
            "biography text not null);";
             db.execSQL(CREATE_TBL);
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        if (oldVersion < 2) {
            final String ALTER_TBL = 
                "ALTER TABLE " + ANIMALS_TABLE +
                " ADD COLUMN biography text not null;";
            db.execSQL(ALTER_TBL);
        }
    }
}

This method of upgrading is the correct way to modify tables without losing user data, especially if the app had been released to public already.