Summary of Database Management Systems.

By -

Summary

This chapter examined the database approach to data manag ment and showed how this approach enables business organ zations to overcome data redundancy and the associated problems that plague the flat-file approach to data management. It showed that the database concept is composed of four dynamically interrelated components: users, the database management system, the database administrator, and the physical database. The DBMS stands between the physical database and the user community. Its principal function is to provide a controlled and secure environment for the database. This is achieved through software modules, such as a query language, a data definition language, and a data manipulation language. The DBMS also provides security against human error and natural disaster through various backup and recovery modules.

Database models are abstract representations of data about entities, events, and activities, and their relationships within an organization. The focus of attention was on the relational model. A number of database design topics were covered, including data modeling, the creation of user views from ER diagrams, and data normalization techniques. Finally, the chapter presented a number of issues associated with distributed databases. It examined three possible database configurations in a distributed environment: centralized, partitioned, and the replicated databases.

Comments

Post a Comment

Popular posts from this blog

The Conversion Cycle:The Traditional Manufacturing Environment

By -
Image
The Traditional Manufacturing Environment The conversion cycle consists of both physical and information activities related to manufacturing products for sale. The context-level data flow diagram (DFD) in Figure 7-1 illustrates the central role of the conversion cycle and its interactions with other business cycles. Production is triggered by customer orders from the revenue cycle and/or by sales forecasts from marketing. These inputs are used to set a production target and prepare a production plan, which drives production activities. Purchase requisitions for the raw materials needed to meet production objectives are sent to the purchases procedures (expenditure cycle), which prepares purchase orders for vendors. Labor used in production is transmitted to the payroll system (expenditure cycle) for payroll processing. Manufacturing costs associated with intermediate work-in-process and finished goods (FG) are sent to the general ledger (GL) and financial reporting system. Dependin
Read more

The Revenue Cycle:Manual Systems

By -
Image
Manual Systems The purpose of this section is to support the system concepts presented in the previous section with models depicting people, organizational units, and physical documents and files. This section should help you envision the segregation of duties and independent verifications, which are essential to effective internal control regardless of the technology in place. In addition, we highlight inefficiencies intrinsic to manual systems, which gave rise to modern systems using improved technologies. SALES ORDER PROCESSING The system flowchart in Figure 4-12 shows the procedures and the documents typical to a manual sales order system. In manual systems, maintaining physical files of source documents is critical to the audit trail. As we walk through the flowchart, notice that in each department, after completion of the assigned task, one or more documents are filed as evidence that the task was completed. Sales Department The sales process begins with a customer cont
Read more

HIPO (hierarchy plus input-process-output)

By -
Image
HIPO (hierarchy plus input-process-output) 64.1 Purpose The HIPO (Hierarchy plus Input-Process-Output) technique is a tool for planning and/or documenting a computer program. A HIPO model consists of a hierarchy chart that graphically represents the program’s control structure and a set of IPO (Input-Process-Output) charts that describe the inputs to, the outputs from, and the functions (or processes) performed by each module on the hierarchy chart. 64.2 Strengths, weaknesses, and limitations Using the HIPO technique, designers can evaluate and refine a program’s design, and correct flaws prior to implementation. Given the graphic nature of HIPO, users and managers can easily follow a program’s structure. The hierarchy chart serves as a useful planning and visualization document for managing the program development process. The IPO charts define for the programmer each module’s inputs, outputs, and algorithms. In theory, HIPO provides valuable long-term documentation. However
Read more