Chapter 11
CHAPTER 11: SYSTEMS DESIGN – DATABASE, NETWORK, PROGRAM AND CONTROL
1. Database
A central source of data meant to be shared by many users for a variety of applications.
2. Database Types
i. Hierarchical
ii. Network
iii. Relational
iv. Object Oriented
v. Object Relational
3. Relational Database
It is one that allows table to be related to each other so that changes in one table are reflected in other table automatically.
4. Database Software
It contained a data definition language (DLL) to create and populate database and describe the logical views of the user.
5. Database Design Guidelines
i. Determine the purpose of the database
ii. Identify the entities
iii. Determine the relationship among the entities.
iv. Draw the entity relationship diagram
6. Types of relationship
i. One –to-one
ii. One-to-many
iii. Many-to-many
7. Guidelines to draw ERD
i. Identify the entities
ii. Add diamonds to represent important relationships between the entities
iii. Specify the associations of these relationships
· Entities represented by rectangles while relationships by lines and diamonds.
8. Conversion the ERD into a Relational Database
i. Create tables for each entity
ii. Identify attributes for each table
a. Identify keys
i. Primary Key
ii. Secondary Key
iii. Concatenated Key
b. Specify data types and field sizes
iii. Normalize the table
9. Network Design
i. Distributed Information System
ii. Client-server Architecture
iii. Intranet
iv. Extranet’
v. Network Cost
10. Evaluating Networks
i. Functional Capabilities and Limitations
- How fast, user numbers, cost per volume, and long without errors.
ii. Ease of use
- Understandability, required effort to become proficient and geographic coverage.
iii. Compatibility
- Does the network conform to accepted industry standards
iv. Maintainability
- Possibility to significantly increase/decrease capacity and important aspects without major disruptions.
11. Matters To Consider Determining Which Topology To Be Used
i. The distance between the computers
ii. The frequency and volume of data transmissions
iii. The processing capability of each computer
12. Basic Connection Topology
i. Star Topology
It interconnects many nodes through a central computer system, which called a server.
ii. Ring Topology
Each node is connected to the adjacent node in a circular fashion.
iii. Bus Topology
All nodes are attached to the “bus”.
iv. Hybrid Topology
A pure form of any one of the three basic topologies is seldom found in practice.
13. Types Of Network
i. LAN (Local Area Network)
It is a network that interconnects computers and communication devices within an office or series of offices, distance between few hundred meters to.
ii. WAN (Wide Area Network)
14. Communication Channels
- Link the different components of a network
- Two types of communication channels
i. Wired Channels
- Use physical wires @ cables to transmit information
- Types of wired channels:
·Twisted Pair
Made from copper, twisted in pairs, and is the most popular medium since it is relatively inexpensive.
·Coaxial
It made from copper but offers higher transmission speed than twisted pair.
·Fiber optic
It made from thousands of very thin filaments of fiberglass and use light digital as a digital information carrier.
ii. Wireless Channel
Such as Public Switch Telephone Network (PSTN)
15. Network Protocol
Those are rules and standards governing the design of hardware and software that permit users of networks manufactured by different vendors to communicate and share data.
16. Pseudocode Comes From The Five Modules In The Structure Diagram
i. Accept UserID
ii. Accept PartNum
iii. Check whether the record has already existed
iv. If already existed, the information will be screened
v. If not, “Parts do not exist” will be screened
17. System Control
i. Data Security
It is controls that safeguard computer hardware and software.
ii. Data Control
It is a quality control measure to ensure the accuracy of data entering into the system.
iii. Contingency Planning
- It lays down the procedures to be followed before, during and after an emergency.
- It is to ensure continuity of operations and availability of critical computing resources in the event of an emergency.
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