public T ExecuteScalar <T>(QueryModel queryModel)
        {
            SqliteQueryModelVisitor visitor = new SqliteQueryModelVisitor(_context);

            visitor.VisitQueryModel(queryModel);

            var result = _connection.ExecuteScalar(visitor.GetSql(), visitor.Parameters.ToDictionary());  //, _transaction );

            return((T)Convert.ChangeType(result, typeof(T)));
        }