anchor.diff:  
     /// for DELETE sql query
     /// return the number of changes made
  -  Future<int> delete(String sql, [List arguments]) => update(sql, arguments);
  +  Future<int> rawDelete(String sql, [List arguments]) => update(sql, arguments);
   
     /// for SELECT sql query
  -  Future<List<Map<String, dynamic>>> query(String sql, [List arguments]) async {
  -    return synchronized(lock, () async {
  +  Future<List<Map<String, dynamic>>> rawQuery(String sql, [List arguments]) async {
  +    return synchronized(_lock, () async {
         return await Sqflite._channel.invokeMethod(
             _methodQuery, <String, dynamic>{
           _paramId: _id,
  
positive.code:   }
  }
  
  class Transaction {
    bool successfull;
  }
  
  class Database {
    String get path => _path;
    String _path;
    int _id;
    Database._(this._path, this._id);
    var lock = new SynchronizedLock();
  
    @override
    String toString() {
  
negative.code: 
    /// for sql without return values
    Future execute(String sql, [List arguments]) async {
      return synchronized(_lock, () async {
        await Sqflite._channel.invokeMethod(_methodExecute, <String, dynamic>{
          _paramId: _id,
          _paramSql: sql,
  