itss 4300 exam 2 ch. 9

Module

- (1) A design segment that can be implemented as an autonomous unit and is sometimes linked to produce a system. (2) An information system component that handles a specific function, such as inventory, orders, or payroll.

transaction log backup

- A backup of only the transaction log operations that are not reflected in a previous backup copy of the database.

full backup

- A complete copy of an entire database saved and periodically updated in a separate memory location. A full backup ensures a full recovery of all data after a physical disaster or database integrity failure.

Database Life Cycle (DBLC)

- A cycle that traces the history of a database within an information system. The cycle is divided into six phases: initial study, design, implementation and loading, testing and evaluation, operation and maintenance, and evolution.

top-down design

- A design philosophy that begins by defining the main structures of a system and then moves to define the smaller units within those structures. In database design, this process first identifies entities and then defines the attributes within the entities.

Bottom-up design

- A design philosophy that begins by identifying individual design components and then aggregates them into larger units. In database design, the process begins by defining attributes and then groups them into entities.

description of operations

- A document that provides a precise, detailed, up-to-date, and thoroughly reviewed description of the activities that define an organization's operating environment.

differential backup

- A level of database backup in which only the last modifications to the database are copied.

centralized design

- A process by which all database design decisions are carried out centrally by a small group of people. Suitable in a top-down design approach when the problem domain is relatively small, as in a single unit or department in an organization.

decentralized design

- A process in which conceptual design models subsets of an organization's database requirements, which are then aggregated into a complete design. Such modular designs are typical of complex systems with a relatively large number of objects and procedures.

conceptual design

- A process that uses data-modeling techniques to create a model of a database structure that represents real-world objects as realistically as possible. The design is both software- and hardware-independent.

database role

- A set of database privileges that could be assigned as a unit to a user or group.

physical design

- A stage of database design that maps the data storage and access characteristics of a database. Because these characteristics are a function of the types of devices supported by the hardware, the data access methods supported by the system physical design are both hardware- and software-dependent. See also physical model.

clustered tables

- A storage technique that stores related rows from two related tables in adjacent data blocks on disk.

database fragment

- A subset of a distributed database. Although the fragments may be stored at different sites within a computer network, the set of all fragments is treated as a single database. See also horizontal fragmentation and vertical fragmentation.

information system (IS)

- A system that provides for data collection, storage, and retrieval; facilitates the transformation of data into information; and manages both data and information. An information system is composed of hardware, the DBMS and other software, database(s), people, and procedures.

Virtualization

- A technique that creates logical representations of computing resources that are independent of the underlying physical computing resources.

1. What are business rules? Why are they important to a database designer?

- Business rules is a brief and precise description of a policy, procedure, or principle within a specific organization's environment. Business rules, derived from a detailed description of an organization's operations, help to create and enforce actions within that organizations environment. - - Knowing the business rules enables the designer to fully understand how the business work and what role the data plays within company operations. Consequently, the designer must identify the company's business rules and analyze their impact on the nature, role, and scope of data.

1. Discuss the distinction between centralized and decentralized conceptual database design.

- Centralized conceptual data design - - A process by which all database design decisions are carried out centrally by a small group of people. Suitable in a top-down design approach when the problem domain is relatively small, as in a single unit or department in an organization. - - is productive when the data component has a relatively small number of objects and procedures. The design can be carried out and represented in a fairly simple database - Decentralized conceptual data design - - A process in which conceptual design models subsets of an organization's database requirements, which are then aggregated into a complete design. Such modular designs are typical of complex systems with a relatively large number of objects and procedures. - - might be used when the system's data component has a considerable number of entities and complex relations on which very complex operations are performed. Decentralized design is also often used when the problem itself is spread across several operational sites and each element is a subset of the entire data set.

1. List and briefly explain the activities involved in the verification of an ER model.

- Data model verification is one of the last steps in the conceptual design stage, and it is one of the most critical. In this step, the ER model must be verified against the proposed system processes to corroborate that they can be supported by the database model. - - The ER Model Verification Process is: - STEP ACTIVITY - 1 Identify the ER model's central entity. - 2 Identify each module and its components. - 3 Identify each module's transaction requirements: - Internal: updates/inserts/deletes/queries/reports - External: module interfaces - 4 Verify all processes against the module's processing and reporting requirements. - 5 Make all necessary changes suggested in Step 4. - 6 Repeat Steps 2-5 for all modules.

minimal data rule

- Defined as "All that is needed is there, and all that is there is needed." In other words, all data elements required by database transactions must be defined in the model, and all data elements defined in the model must be used by at least one database transaction.

1. What three levels of backup may be used in database recovery management? Briefly describe what each backup level does.

- Full backup - - Or dump; A complete copy of an entire database saved and periodically updated in a separate memory location. A full backup ensures a full recovery of all data after a physical disaster or database integrity failure. - Differential backup - - A level of database backup in which only the last modifications to the database are copied. - Transaction log backup - - A backup of only the transaction log operations that are not reflected in a previous backup copy of the database.

1. What is an information system? What is its purpose?

- Information system is a system that provides for data collection, storage, and retrieval; facilitates the transformation of data into information; and manages both data and information. An information system is composed of hardware, the DBMS and other software, database(s), people, and procedures. - - The purpose of information technology is to transform data into useful information that can be used to make decisions

1. List and briefly explain the four steps performed during the logical design stage.

- Logical Design Steps - STEP ACTIVITY - 1 Map the conceptual model to logical model components. - - The first step in creating the logical design is to map the conceptual model to the chosen database constructs. - 2 Validate the logical model using normalization. - - The logical design should contain only properly normalized tables. The process of mapping the conceptual model to the logical model may unveil some new attributes or the discovery of new multivalued or composite attributes. - 3 Validate the logical model integrity constraints. - - The translation of the conceptual model into a logical model also requires definition of the attribute domains and appropriate constraints. - - 4 Validate the logical model against user requirements. - - The final step in the logical design process is to validate all logical model definitions against all end-user data, transaction, and security requirements.

1. What steps are required in the development of an ER diagram? (Hint: See Table 9.3.)

- STEP ACTIVITY - 1 Identify, analyze, and refine the business rules. - 2 Identify the main entities, using the results of Step 1. - 3 Define the relationships among the entities, using the results of Steps 1 and 2. - 4 Define the attributes, primary keys, and foreign keys for each of the entities. - 5 Normalize the entities. (Remember that entities are implemented as tables in an RDBMS.) - 6 Complete the initial ER diagram. - 7 Validate the ER model against the end users' information and processing requirements. - 8 Modify the ER model, using the results of Step 7.

1. How do systems analysis and systems development fit into a discussion about information systems?

- System analysis is the process that establishes the need for an information system and its extent. - System development is the process of database design and implementation. - They both play an integral part in the System Development Life Cycle (SDLC).

1. What does the acronym DBLC mean, and what does a DBLC portray?

- The acronym DBLC means Database Life Cycle. - The DBLC portrays the history of the database from its establishment to the point when it becomes outdate. - The DBLC contains six phases: - database initial study, database design, implementation and loading, testing and evaluation, operation, and maintenance and evolution.

1. What does the acronym SDLC mean, and what does an SDLC portray?

- The acronym SDLC means System Development Life Cycle. - SDLC portrays the history of an information system. The SDLC provides the big picture within which database design and application envelopment can be mapped out and evaluated. - The traditional SDLC is divided into 5 phases: - planning, analysis, detailed systems design, implementation, and maintenance.

Systems Development Life Cycle (SDLC)

- The cycle that traces the history of an information system. The SDLC provides the big picture within which database design and application development can be mapped out and evaluated.

1. What is the data dictionary's function in database design?

- The data dictionary in database design serves to define and describe the data elements, their structures, relationships, and constraints. It acts as a central repository of metadata, providing a comprehensive understanding of the database schema and facilitating effective integration, consistency, and management of data within the system. It helps in ensuring data integrity by enforcing standards for data quality and consistency

module coupling

- The extent to which modules are independent of one another.

Boundaries

- The external limits to which any proposed system is subjected. These limits include budgets, personnel, and existing hardware and software.

1. What is the minimal data rule in conceptual design? Why is it important?

- The minimal data rule is defined as: - - "All that is needed is there, and all that is there is needed" - - In other words, all data elements required by database transactions must be defined in the model, and all data elements defined in the model must be used by at least one database transaction. - - For an information system to function effectively, it must support current and future requirement

Scope

- The part of a system that defines the extent of the design, according to operational requirements.

systems development

- The process of creating an information system.

database development

- The process of database design and implementation.

systems analysis

- The process that establishes the need for an information system and its extent.

1. What factors are important in a DBMS software selection?

- The selection of DBMS software is critical to the information system's smooth operation. - - Although the factors that affect the purchasing decision vary from company to company, some of the most common are: - - Cost - - This includes the original purchase price, along with maintenance, operational, license, - installation, training, and conversion costs. - - DBMS features and tools - - Some database software includes a variety of tools that facilitate application - development. - - Underlying model - - This can be hierarchical, network, relational, object/relational, or object-oriented. - - Portability - - A DBMS can be portable across platforms, systems, and languages. - - DBMS hardware requirements - - Items to consider include processor(s), RAM, disk space, and so on.

Cohesivity

- The strength of the relationships between a module's components. Module cohesivity must be high.

1. Discuss the distinction between top-down and bottom-up approaches in database design.

- Top-down database design - - A design philosophy that begins by defining the main structures of a system and then moves to define the smaller units within those structures. In database design, this process first identifies entities and then defines the attributes within the entities. - - Bottom-up database design - - A design philosophy that begins by identifying individual design components and then aggregates them into larger units. In database design, the process begins by defining attributes and then groups them into entities.