Android 在删除受影响的行之前识别它们

我想知道是否有可能在实际运行删除之前检查受删除影响的行数：

 public static int deletePremixable(Context context, Premixable premixable) {
        Long id = premixable.getId();

        SQLiteDatabase db = getWritableDatabase(context);

        String selection = PremixableEntry._ID + "=?";
        String[] selectionArgs = new String[]{String.valueOf(id)};

        // Here I would like to do something like 
        // if(db.deleteAffectedRows((PremixableEntry.TABLE_NAME, selection, selectionArgs) > 1) {
        //     throw Exception('It should never be more than one line deleted here!');
        // }

        return db.delete(PremixableEntry.TABLE_NAME, selection, selectionArgs);
    }

---

您可以使用事务，例如

db.beginTransaction();
try {

    // delete and check the result
    // you can use several queries

    if (everything_ok) {
        db.setTransactionSuccessful();
    }

} finally {
    // if the transaction was not set successful
    // all changes since beginTransaction will be reverted
    db.endTransaction();
}

---

您可以使用事务，例如

db.beginTransaction();
try {

    // delete and check the result
    // you can use several queries

    if (everything_ok) {
        db.setTransactionSuccessful();
    }

} finally {
    // if the transaction was not set successful
    // all changes since beginTransaction will be reverted
    db.endTransaction();
}

---

您可以检查有多少行会受到影响

Cursor res = db.rawQuery("SELECT * FROM " + PremixableEntry.TABLE_NAME + " WHERE " + selection, selectionArgs);
if (res.getCount() == 1){
       //do the delete
}

---

您可以检查有多少行会受到影响

Cursor res = db.rawQuery("SELECT * FROM " + PremixableEntry.TABLE_NAME + " WHERE " + selection, selectionArgs);
if (res.getCount() == 1){
       //do the delete
}