????????????????????????????SQL???д?????????????SQL????????SQLite???????????????и?????????????Щ??????????Щworkaround?????Щ???????????????????????(update)????У?????ò????????????????SQLite?????DROP COLUMN????workaround??

????????????и???(upgrade)??????SQL??????????????????onUpgrade?????е???SQL?????????????????????
 
@Override
public void onUpgrade(SQLiteDatabase db?? int oldVersion?? int newVersion) {     
if (newVersion > oldVersion) {
    switch (oldVersion) {
        case 1:
            executeSQLScript(database?? "update_v2.sql");
        case 2:
            executeSQLScript(database?? "update_v3.sql");
    }
}
}

????????δ???????????????????????????????????????ж?????????汾??????????????汾??????onUpdategrade()???????????汾?????????????????????п????????????汾???????????????????????????????????????????????????????????????????????

?????????????case???????????break????????????????е?SQL?????????????汾????(updates)????????汾?????????????????汾1????(upgrade)???汾3????????????д?汾1????(upgrade)???汾2?????????????д?汾2????(upgrade)???汾3???????????????????汾2???????????а汾2???汾3?????(upgrade)?????

?????????????????????(upgrade)????????????????????汾???μ??°汾???????????????Щ????д???????????????????κ?????汾???????????????????Java??????????????????DB_VERION????????????????????仯???????

????????

??????Android????????????????У?SQLite??????????洢?????????????????????????????????????κ?????????????????С???????????????????????仯??????С????С???

??????????????????д??SQL?????(???????????????????????д????????ж??????浽???????????Щ??????????SQL???????)??????浽????????????Ч??????????????????????????????????д???????????????θ???(upgrade)???????????????????????????????