MIS 321

What are the steps in creating a decision table?

1. Name the conditions and the values that each condition can assume 2. Name all possible actions that can occur 3. List all possible rules 4. Define the actions for each rule 5. Simplify the decision table

In the context of a relational database model, what is a "relation"?

A 2D table of data in which each cell has a value

Functional dependency

A constraint between two attributes in which one attribute is determined by the value of another attribute.

Supertype

A generic entity type that has a relationship with one or more subtype Student

What is "Structured English"?

A modified form of English that is similar to pseudocode but more user oriented.

What is an "attribute" of an entity? Illustrate with an example.

A named property or characteristic for an entity that is important to the user

What is a "foreign key"?

A primary key in another table

What does a "relationship" on an E-R diagram represent? Is there more than one way to represent a relationship on an E-R diagram?

An association between the instance of entity types. Yes through various cardinalities.

How might CASE diagramming tools come in handy during systems analysis? Illustrate with an example.

Automates checking for incomplete, inconsistent specifications and automates tasks EXAMPLE: Diagramming to create process, logic, and data models

Why do some systems developers consider the data model to be one of the most important components of a system requirement specification?

Because it is a simple way to organize the data process(?)

What are the advantages of having a CASE repository?

Being able to already have pre-defined data elements when reading out data structures.

How reduce the size and complexity of a decision table?

By removing any rules with impossible actions

Overlap rule

Can be part of both subtypes

Disjoint rule

Can only be member of one subtype

What is a "candidate key"? An "identifier" (an "identifier" is also referred to as a "primary key")? What criteria should be considered when selecting a primary key? Why is it important to designate a primary key?

Candidate Key: List of all the attributes Identifier: A candidate key that has been selected, a primary key A primary key should be a unique identifying attribute. It is an easier way to create links and find information.

What is CASE? Why is CASE used by systems developers?

Computer Aided Software Engineering, It is used my system developers to map out processes and data flows. It supports the early phases (LOWER CASE TOOL) of the SDLC by creating diagrams and repository(Project Dictionary) for the project. It saves all details and is easy to generate reports of repository information.

What is a relational database model?

Data represented as relations.

List the deliverables from the conceptual data modeling part of the analysis phase.

ER Diagram Full set of entries about data objects that will be stored in the data dictionary

What type of information relating to data modeling is stored in the project dictionary? Illustrate with examples.

Entities Entity attributes Relationship Business rules

What is the difference between an "entity type" and an "entity instance"?

Entity type: collection of entities that share common properties or characteristics Entity Instance: Single occurrence of an entity type

List the ideal characteristics of an entity identifier attribute

Give a descriptive noun

What is a "triggering operation" and what purpose does it serve? Illustrate with an example.

Governs the validity of data manipulation operations. It adds, updates, and deletes

Modification anomaly

If one cell changes then you have to change other cells

What is a CASE "repository"? What specific type of information would be useful to store in the repository?

It is the same thing as a project dictionary. This is useful for storing data elements.

How are the ER diagrams (i.e., "conceptual data models") -- which are generated during the Analysis stage -- used for database design? What is a relational database model?

Minimize redundancies and anomalies.

What is the formula that is used to calculate the number of rules a decision table must cover?

Multiply the values by the conditions.

What type of shorthand notation is used to represent a relation?

NAME OF TABLE(Attribute_1,etc)

Do ER diagrams replace DFDs? Or do ER diagrams supplement DFDs? Please explain.

NO!!!!!! they supplement DFDs. Each data store represents a portion of a er diagram and the attributes of each entity are included in the data stores

What is the degree of a relationship?

Number of entity types that participate in the relationship.

What is meant by the "cardinality" of a relationship?

Number of instances of an entity that can be associated with each instance

Which types of relationships can have attributes associated with them

One to one and many to many

What does it mean for a relation to be in second normal form? Third normal form? Be able to illustrate each with an example.

Partial dependencies Transitive dependencies

What information about a system is represented on an entity-relationship data model? Illustrate with an example.

Primary keys and attributes like we can find on an ER diagram

What is an "associative entity"?

Relationships with one or more attributes. Like a shared attribute in a many to many relationship.

Why is it useful to provide "domain" definitions for data? Illustrate with an example.

Saves effort for describing attribute characteristics. EXAMPLE: VA3

What does the term "limited entry" mean in a decision table?

Simplest form of a decision table where the outcome is either true or false (boolean)

What is the purpose of normalizaiton

Simplicity, non-redundancy, and minimal maintenance.

How can Structured English be used to represent sequence, conditional statements, and repetition in an information systems process?

Structured English uses control structures, conditional statements and repetition statements similar to computer code. Though, it's much more user oriented, so while the complex logic is still there, it's quite easy to read.

Why would Structured English be a useful way to represent the processing associated with a functional primitive process?

Structured English would be useful when representing functional primitives because it has the capability to give a concise and exact description of the process in one page or less.

Subtype

Subgrouping of the entities in an entity type that is meaningful to the organization that shares common attributes Undergrad or grad

Physical design

Technological

Logical design

Technology independent

What is meant by the "degree of a relationship"?

The number of entity types that participate in a relationship. Unary, Binary, Ternary.

What role do "business rules" play in data modeling?

They preserve the integrity of the data model.

What can be done to enhance the formatting and readability of Structured English?

To enhance readability, structured English uses indents within the scope of conditional statements so it is easy to follow the flow of the process. Line spacing also improves readability, within the context of structured English.

What are examples of different types of CASE tools? Please illustrate with examples.

Visible Analyst and Visible Developer

Provide an example of a situation when it would it make sense for a relationship to have an attribute(s).

When a relationship action needs to be specified.

Delete anomaly

When certain attributes are lost due to the deletion of other attributes

What is a transitive dependency?

When there is functional dependency within non-primary attributes

Insertion anomaly

You cant create a new entry without giving it other attributes

What are examples of CASE tool usage for the different phases of the SDLC? Be able to provide examples.

http://i.imgur.com/vZBcbdA.jpg