public static int CountByRawSql(this DbContext dbContext, string sql, params KeyValuePair<string, object>[] parameters)
{
  int result = -1;
  SqlConnection connection = dbContext.Database.GetDbConnection() as SqlConnection;

  try
  {
    connection.Open();

    using (SqlCommand command = connection.CreateCommand())
    {
      command.CommandText = sql;

      foreach (KeyValuePair<string, object> parameter in parameters)
        command.Parameters.AddWithValue(parameter.Key, parameter.Value);

      using (DbDataReader dataReader = command.ExecuteReader())
        if (dataReader.HasRows)
          while (dataReader.Read())
            result = dataReader.GetInt32(0);
    }
  }

  // We should have better error handling here
  catch (System.Exception e) { }

  finally { connection.Close(); }

  return result;
}