无法将类型为“ System.DBNull”的对象转换为类型为“ System.String”的对象
我的应用程式中出现上述错误。这是原始代码 public string GetCustomerNumber(Guid id) { string accountNumber = (string)DBSqlHelperFactory.ExecuteScalar(connectionStringSplendidmyApp, CommandType.StoredProcedure, "GetCustomerNumber", new SqlParameter("@id", id)); return accountNumber.ToString(); } 我换成 public string GetCustomerNumber(Guid id) { object accountNumber = (object)DBSqlHelperFactory.ExecuteScalar(connectionStringSplendidCRM, CommandType.StoredProcedure, "spx_GetCustomerNumber", new SqlParameter("@id", id)); if (accountNumber is System.DBNull) { return string.Empty; } else { return accountNumber.ToString(); } } 有没有更好的办法解决这个问题?