Android SQLite Database, WHY drop table and recreate on upgrade

Question

In the tutorials I am following and a lot of more places I see this, onUpgrade -> drop table if exists, then recreate table.

What is the purpose of this?

private static class DbHelper extends SQLiteOpenHelper{      public DbHelper(Context context) {         super(context, DATABASE_NAME, null, DATABASE_VERSION);     }      @Override     public void onCreate(SQLiteDatabase db) {         db.execSQL("CREATE TABLE " + DATABASE_TABLE + " (" +                 KEY_ROWID + " INTEGER PRIMARY KEY AUTOINCREMENT, " +                 KEY_NAME + " TEXT NOT NULL, " +                 KEY_HOTNESS + " TEXT NOT NULL);"         );       }      @Override     public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {         db.execSQL("DROP TABLE IF EXISTS " + DATABASE_TABLE);         onCreate(db);     }        } 

Answer 1

I agree when you upgrade you should be adding columns or adding tables to your database. Most of the onupgrade samples actually suck because why am I deleting all this data then recreating the table? I found this blog entry I call it the Adams Incremental Update Method. It also handles situations where users may have not upgraded your app with each release.

Here is a good blog on sqlite onupgrade that doesn't do drop table.