电子商务的类型有以下几种。 (1)企业与消费者之间的电子商务(Business to Consumer，即B2C)。 (2)企业与企业之间的电子商务(Business to Business，即B2B)。 (3)消费者与消费者之间的电子商务(Consumer to Consumer，即C2C)。 (4)线下商务与互联网之间的电子商务(Online To Offline，即O2O)。 在题目中独立咨询师属于C，而企业属于B，因此这种类型的电子商务是C2B。
39. 决策支持系统的基本组成部分包括______。
A.数据库子系统、模型库子系统、数据解析子系统和数据查询子系统
B.数据库、数据字典、数据解析模块和数据查询模块
C.数据库子系统、模型库子系统、决策算法子系统
D.数据库子系统、模型库子系统、推理部分和用户接口子系统
A B C D
D
决策支持系统(Decision Support System, DSS)是辅助决策者通过数据、模型和知识，以人机交互方式进行半结构化或非结构化决策的计算机应用系统。它是MIS向更高一级发展而产生的先进信息系统。它为决策者提供分析问题、建立模型、模拟决策过程和方案的环境，调用各种信息资源和分析工具，帮助决策者提高决策水平和质量。但是，DSS不可以代替决策者。 DSS基本结构主要由四个部分组成，分别是数据库子系统、模型库子系统、推理部分和用户接口子系统。
The purpose of the systems analysis phase is to build a logical model of the new system. The first step is ______，where you investigate business processes and document what the new system must do to satisfy users. This step continues the investigation that began during the ______. You use the fact-finding results to build business models, data and process models, and object models. The deliverable for the systems analysis phase is the ______, which describes management and user requirements, costs and benefits, and outlines alternative development strategies. The purpose of the systems design phase is to create a physical model that will satisfy all documented requirements for the system. During the systems design phase, you need to determine the ______，which programmers will use to transform the logical design into program modules and code. The deliverable for this phase is the ______, which is presented to management and users for review and approval.
关系运算，与该关系表达式等价的是______。将该关系代数表达式转换为等价的SQL语句如下：
深色：已答题 浅色：未答题