DataAccessLayer.DataBase.GetAccountById C# (CSharp) Method

        public Account GetAccountById(Guid id)
        {
            string queryString =
               "SELECT [dbo].accounts.accountid, login, password, mail, city, country, [dbo].accounts.name, [dbo].Roles.Name " +
                "FROM [dbo].accounts, [dbo].UsersRoles, [dbo].Roles " +
                "WHERE ([dbo].accounts = @accountid) AND ([dbo].Roles.RoleId = [dbo].UsersRoles.RoleId);";

            using (SqlConnection connection = new SqlConnection(_connectionString))
            {
                var command = new SqlCommand(queryString, connection);

                command.Parameters.AddWithValue("accountid", id);

                connection.Open();

                var reader = command.ExecuteReader();

                if (reader.Read())
                {
                    return new Account()
                    {
                        Id = (Guid)reader[0],
                        Login = (string)reader[1],
                        Email = (string)reader[2],
                        City = (string)reader[3],
                        Country = (string)reader[4]
                    };
                }
                return null;
            }
        }