private static final String TABLE_MAIN_CREATE = \"CREATE TABLE IF NOT EXISTS \" + TABLE_MAIN_NAME + \" ( a INTEGER, b LONG, c TEXT, d TEXT, e DATETIME, f TEXT)\";
pr
You need not call onCreate in onUpgrade. Doing db.execSQL(TABLE_MAIN_UPGRADE) in enough for update.
Now you should clear data of your application. To do this re-install the app or execute in android shell