AIS Exam#2 – Flashcards
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Database application
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An application program, (or set of related programs), that is used to perform a series of database activities, (such as create, read, update, and delete), on behalf of database users.
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*File Processing System*
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*= a paper system*
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*Problems with File Processing system*
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*Redundancy*. *Inconsistency*: a change in a file in one department will not be the same in another department.
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Traditional File Processing Systems
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*No databases*. *Computer file processing systems.* Computers store, manipulate, and retrieve large files of data.
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Disadvantages of File Processing Systems
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1. Program-data dependence. 2. Duplication of data. 3. Limited data sharing. 4. Lengthy development times. 5. Excessive program maintenance.
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Program-data dependence
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*File descriptions are stored within each program*. *Any change to a file* structure *requires changes to* the file descriptions for *ALL programs* that access that file.
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Program-data Independence
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*Data descriptions are stored in a central location, (repository).* Allows data to change without changing the programs that process that data.
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Limited data sharing
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*Each application has its own private files.* *File incompatibility between applications.* Users have limited ability to share data outside of their own applications. Difficult to draw data: need to draw several incompatible files from separate systems.
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Improved data sharing
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One unified database. Multiple users have access to data in the database via different user views. Users can easily share data.
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Data model
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Graphical systems used to capture the nature and relationships among data.
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Data models
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Are made up of *entities*, *attributes*, and *relationships*.
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Relational database
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A database that represents data as a collection of tables in which all data relationships are represented by common values in related tables.
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*SQL*
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*Structured Query Language.*
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*DBMS*
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*Database Management System*. *NOT a database, it is a software.*
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Database management system
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A software system that is used to create, maintain, and provide controlled access to user databases.
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How does *DBMS* function?
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It enables end users ; application programmers to share data, and, it enables data to be shared among multiple applications.
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Systems Development Life Cycle (SDLC)
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The traditional methodology, or *steps*, used to develop, maintain, and replace *information systems*.
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What are the steps in SDLC?
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1. Planning. 2. Analysis. 3. Design. 4. Implementation. 5. Maintenance.
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ERD
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*Entity-Relationship Diagram* (E-R diagram). A graphical representation of an entity-relationship model.
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Business Rules
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Statements that define or *constrain* some aspect(s) of the business. They are intended to assert business structure, or to control, or influence the behavior of the business. Also known as "integrity constraint".
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Why are Business Rules important?
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They help ensure that information systems work right, and that users of the information understand what they enter, and see.
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Examples of Business Rules affecting data processing, and data storage.
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"A student may register for a section of a course only if he or she has successfully completed the prerequisites for that course." "A preferred customer qualifies for a 10 percent discount, unless he has an overdue account balance."
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Entity
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A *person*, a *place*, an *object*, an *event*, or a *concept* in the user environment about which the organization wishes to maintain data.
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Entity type
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A collection of entities that share common properties or characteristics. For example, *EMPLOYEE* in a company's database, represents many employees.
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Entity Instance
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A single occurrence of an entity type. For example, employee Joe Diaz, within the "EMPLOYEE" entity type.
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Relationship
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An association representing an interaction among the instances of on or more entity types that is of interest to the organization. Relationships & their characteristics: degree, & cardinality, represent business rules.
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Relationship type
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= cardinality. A meaningful association between, or among, entity types. Allow us to answer questions that could not be answered given only the entity types.
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Relationship degrees
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The number of entity types that participate in a relationship.
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3 most common relationship degrees in E-R models:
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Degree 1: Unary. One to one., Degree 2: Binary. One to Many. Or Many to Many., Degree 3: Ternary. Simultaneous among three entity types.
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Example of One to One.
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person, "is married to", person.
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Example of One to Many.
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Employee, "manages", Employee(s).
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Example of Many to Many.
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Student(s), "registers for, Course(s).
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Composite attributes
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Attributes that can be divided into smaller sub-parts. These sub-parts represent basic attributes with independent meanings of their own. For example, take Name attributes. We can divide it into sub-parts like First_name, Middle_name, and Last_name.
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Derived attributes
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Attributes whose values are generated from other stored attributes. For example, Account Balance is derived by subtracting Total Debit from Total Credit.
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Identifier attributes
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Called keys or key attributes uniquely identify an instance of an entity. If such an attribute doesn't exist naturally, a new attribute is defined for that purpose. For example, an ID number, or code.
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Cardinality constraint
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A rule that specifies the number of instances of one entity that can, or must, be associated with each instance of another entity.
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*Minimum* cardinality
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The minimum number of instances of one entity that may be associated with each instance of another entity.
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*MAXIMUM* cardinality
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The maximum number of instances of one entity that may be associated with each instance of another entity.
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A database is an organized collection of ________ related data. A) logically. B) physically. C) loosely. D) badly.
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A) logically
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Data processed in a way that increases a user's knowledge is: A) text. B) graphics. C) information. D) hyperlink.
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C) information
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Data that describe the properties of other data are: A) relationships. B) logical. C) physical. D) none of the above.
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D) none of the above.
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One disadvantage of file processing systems is: A) reduced data duplication. B) program-data independence. C) limited data sharing. D) enforcement of integrity constraints.
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C) limited data sharing.
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Program-data dependence is caused by: A) file descriptors being stored in each application. B) data descriptions being stored on a server. C) data descriptions being written into programming code. D) data cohabiting with programs.
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A) file descriptors being stored in each application.
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Because applications are often developed independently in file processing systems: A) the data is always non-redundant. B) unplanned duplicate data files are the rule rather than the exception. C) data can always be shared with others. D) there is a large volume of file I/O.
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B) unplanned duplicate data files are the rule rather than the exception.
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All of the following are primary purposes of a database management system (DBMS) EXCEPT: A) creating data. B) updating data. C) storing data. D) providing an integrated development environment.
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D) providing an integrated development environment.
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Which of the following is NOT an advantage of database systems? A) Redundant data. B) Program-data independence. C) Better data quality. D) Reduced program maintenance.
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A) Redundant data
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Databases may be more expensive to maintain than files because of: A) the need for specialized personnel. B) the complexity of the database environment. C) backup and recovery needs. D) all of the above.
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D) all of the above.
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Which of the following is NOT a cost and/or risk of the database approach? A) Specialized personnel. B) Cost of conversion. C) Improved responsiveness. D) Organizational conflict.
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C) Improved responsiveness
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The logical representation of an organization's data is called a(n): A) database model. B) entity-relationship model. C) relationship systems design. D) database entity diagram.
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B) entity-relationship model.
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In an E-R diagram, there are ________ business rule(s) for every relationship. A) two. B) three. C) one. D) none.
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A) two
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Business policies and rules govern all of the following EXCEPT: A) managing employees. B) creating data. C) updating data. D) removing data.
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A) managing employees.
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Which of the following is NOT a good characteristic of a data name? A) Relates to business characteristics. B) Readable. C) Repeatable. D) Relates to a technical characteristic of the system.
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D) Relates to a technical characteristic of the system
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Customers, cars, and parts are examples of: A) entities. B) attributes. C) cardinals. D) relationships.
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A) entities.
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A person's name, birthday, and social security number are all examples of: A) attributes. B) entities. C) relationships. D) descriptors.
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A) attributes.
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An entity that associates the instances of one or more entity types and contains attributes specific to the relationships is called a(n): A) associative entity. B) connecting entity. C) intersectional entity. D) all of the above.
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A) associative entity.
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The number of entity types that participate in a relationship is called the: A) number. B) identifying characteristic. C) degree. D) counter.
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C) degree.
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A relationship between the instances of a single entity type is called a(n) ________ relationship. A) ternary. B) primary. C) binary. D) unary.
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D) unary
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Physical database design decisions must be made carefully because of impacts on: A) data accessibility. B) response times. C) security. D) all of the above.
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D) all of the above.
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An attribute (or attributes) that uniquely identifies each row in a relation is called a: A) column. B) foreign field. C) primary key. D) duplicate key.
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C) primary key.
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An attribute in a relation of a database that serves as the primary key of another relation in the same database is called a: A) link attribute. B) link key. C) foreign key. D) foreign attribute.
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C) foreign key.
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A primary key that consists of more than one attribute is called a: A) foreign key. B) composite key. C) multivalued key. D) cardinal key.
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B) composite key.
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Which of the following are properties of relations? A) Each attribute has a unique name. B) No two rows in a relation are identical. C) There are no multivalued attributes in a relation. D) All of the above.
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D) All of the above.
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The ________ states that no primary key attribute may be null. A) referential integrity constraint. B) entity integrity rule. C) partial specialization rule. D) range domain rule.
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B) entity integrity rule
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A rule that states that each foreign key value must match a primary key value in the other relation is called the: A) referential integrity constraint. B) key match rule. C) entity key group rule. D) foreign/primary match rule.
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A) referential integrity constraint.
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8) Which of the following are anomalies that can be caused by redundancies in tables? A) Insertion. B) Deletion. C) Modification. D) All of the above.
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D) All of the above
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A relation that contains minimal redundancy and allows easy use is considered to be: A) clean. B) simple. C) complex. D) well-structured.
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D) well-structured.
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Schema
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Listing the table (ENTITY) and its Attributes in text form. Example: CUSTOMER: customer I.d., first_name, last_name, credit SALES_ORDER: order#, date
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