Oracle section 1-3 , 9
When all attributes are single-valued, the database model is said to conform to: 1st Normal Form (*) 4th Normal Form 2nd Normal Form 3rd Normal Form
1st Normal Form (*)
Relationships always exist between
2 entities (or one entity and itself)
Consider an example where an Oracle database works "behind the scenes" for common internet activity. Which of the following best describes a database transaction?
A person searches an airline website to find all available fares for a flight
Which of the following is the best scenario for using supertype/subtype entities
A pet store that sells small animals that need different sized cages and different food. An ice cream store that sells ice cream in sugar cones and regular cones. A grocery store that gives customers a choice of plastic or paper bags. A vehicle dealership that sells boats on trailers, cars, and trucks.
Only managers can approve travel requests' is an example of which of the following?
A procedural business rule.
When you resolve a M:M by creating an intersection entity, this new entity will always inherit:
A relationship to each entity from the original M:M.
When you add the concept of time to your data model, you are
Adding complexity to your model
Which of the following is an example of a structural business rule?
All employees must belong to at least one department.
What is the rule of Second Normal Form? All non-UID attributes must be dependent upon the entire UID. (*) Some non-UID attributes can be dependent on the entire UID. No non-UID attributes can be dependent on any part of the UID. None of the above
All non-UID attributes must be dependent upon the entire UID. (*)
What is the function of logging or journaling in conceptual data models?
Allows you to track the history of attribute values, relationships, and/or entire entities
Which of the following can be added to a relationship? An optional attribute can be created A composite attribute An attribute An arc can be assigned (*)
An arc can be assigned (*)
Many to many relationships between entities usually hide what?
Another entity
To visually represent exclusivity between two or more relationships in an ERD you would most likely use a/an ________. UID Subtype Supertype Arc (*)
Arc
The "Other" subtype is best used:
As an extra subtype to ensure that the list of subtypes is exhaustive. By having an "Other" subtype, all instances of the Supertype will have a subtype to belong to
In the following statements, find two good examples of ENTITY: Instance
BOOK: Biography of Mahatma Gandhi (*) TRAIN: runs DAIRY PRODUCT: milk (*) VEGETABLE: grows
If an intersection entity is formed that contains no attributes of its own, its uniqueness may be modeled by
Barring the relationships to the original entities.
How do you turn "data" into "information"?
By querying it or accessing it
The word "Volatile" means:
Changing constantly; unstable
In a physical data model, an attribute is represented as a/an
Column
Which of the following would be a logical constraint when modeling time for a country entity?
Countries may change their names and/or borders over a period of time.
Which of the following entities most likely contains invalid attributes
Entity: Car. Attributes: Owner Occupation, Owner Salary, Speed (*) Entity: Home. Attributes: Number of Bedrooms, Owner, Address, Date Built Entity: Pet. Attributes: Name, Birthdate, Owner Entity: Mother. Attributes: Name, Birthdate, Occupation, Number of Children
An entity may have which of the following?
Experiences instances (*) Tables None of the above
An entity can be on 2nd Normal Form even if it has repeated values. True or False? Mark for Review (1) Points True False (*)
False
An entity can have repeated values and still be in 1st Normal Form. True or False? Mark for Review (1) Points True False (*)
False
Attributes are written inside the entity to which they belong
False
Creating a Matrix Diagram is a mandatory step in Data Modeling
False
Data Modeling is the last step in the database development process. True or False?
False
Entities are usually verbs
False
Entity names are always plura
False
If the entity CD has the attributes: #number, title, producer, *year, o store name, o store address, this entity is in 3rd Normal Form ("no non-UID attribute can be dependent on another non-UID attribute). True or False? Mark for Review (1) Points True False (*)
False
Many-to-Many relationships are perfectly acceptable in a finished ERD. There is no need to do any more work on them. True or False?
False
No database in the world is ever truly on 3rd Normal Form. Everyone always stops after 2nd Normal Form. True or False? True False (*)
False
Non-transferable relationships can only be mandatory, not optional. True or False?
False
Personal computers (PCs) have been in existence since 1950.
False
Relationships can be either mandatory or optional.
False
The following entity is in 1st normal form: True or False? ENTITY: VEHICLE ATTRIBUTES: REGISTRATION MAKE MODEL COLOR DRIVER PASSENGER 1 PASSENGER 2 PASSENGER 3 True False (*)
False
The overall mission of the Oracle Corporation is to use the internet and fast processing servers to build its own network.
False
This diagram could also be expressed as a supertype/subtype construction. True or False? STUDENT #*ID *FULL NAME O-EYE COLOR (RELATIONSHIP THAT THE BAR IS ON STUDENT COURSE SIDE) True False (*)
False
When reading a relationship between 2 entities, the relationship is only read from left to right
False
A business rule such as "All accounts must be paid in full within 10 days of billing" is best enforced by:
Hiring a programmer to create additional programming code to identify and report accounts past due.
What is the benefit to the users of a system that includes "time"; e.g. Start Date and End Date for Employees
Increased usability and flexibility of a system; e.g., we can the trace the different managers an employee had over time.
Users would interact with which of the following software to access essential business applications? (Choose three)
Internet Browser software (*) Server software Operating System software (*) GUI software (*)
Why is it important to identify and document business rules?
It allows you to create your data model and then check it for accuracy.
How do you know when to use the different types of time in your design
It depends on the functional needs of the system
Which of the following are reasons we create conceptual models?
It facilitates discussion; a picture is worth a thousand words It forms important ideal system documentation It takes into account government regulations and laws It forms a sound basis for physical database design All of the above (*)
How should you handle constraints that cannot be modeled on an ER diagram?
List them on a separate document to be handled programmatically
When resolving a M:M relationship, the new relationships will always be __________ on the many side.
Mandatory
Which of the following are relationship types?
Many to Many One to Many
What uncommon relationship is described by the statements: "Each LINE must consist of many POINTS and each POINT must be a part of many LINES".
Many to Many Mandatory
Examine the following Entity and decide which sets of attributes break the 3rd Normal Form rule: (choose two) ENTITY: TRAIN (SYNONYM: ROLLING STOCK) ATTRIBUTES: TRAIN ID MAKE MODEL DRIVER NAME DEPARTURE STATION NUMBER OF CARRIAGES NUMBER OF SEATS DATE OF MANUFACTURE NUMBER OF CARRIAGES, NUMBER OF SEATS (*) TRAIN ID, MAKE MODEL, DATE OF MANUFACTURE DEPARTURE STATION, DRIVER NAME (*)
NUMBER OF CARRIAGES, NUMBER OF SEATS (*)
What are the three properties that every relationship should have?
Name, optionality, cardinality (*) Name, optionality, arcs A UID bar, a diamond, an arc Transferability, degree, name
Which of the following is the definition for Third Normal Form? All attributes are single valued All attributes are uniquely doubled and independent No non-UID attribute can be dependent on another non-UID attribute (*) An attribute must be dependent upon the entity's entire UID
No non-UID attribute can be dependent on another non-UID attribute (*)
When data is stored in more than one place in a database, the database violates the rules of ___________. Normalcy Replication Normalization (*) Decency
Normalization (*)
Which of the following are examples of e-businesses that use database software?
Online research paper Online personal shopping service (*) Online personal web page Online clothing store (*) Online book store (*)
A customized hat sitting on your friend's head is an example of which model--the conceptual model or the physical model?
Physical Model
Some of the following could be attributes of an ENTITY called PERSON; select the INCORRECT attributes for PERSON.
Priya Hansenna (*) Name Freddy Wilson (*) Age
Modeling historical data produces efficient ways for a business to operate such as:
Providing valuable information via reports to management
If the same relationship is represented twice in an Entity Relationship Model, it is said to be:
Redundant
Which of the following would best be represented by an arc? STUDENT (graduating, non-graduating) STUDENT (senior, junior) STUDENT (will-attend-university, will-not-attend-university) STUDENT ( University, Trade School) (*)
STUDENT ( University, Trade School) (*)
Which of the following pairs of entities is most likely to be modeled as a M:M relationship?
STUDENT and CLASS RENTAL CAR and DRIVER
Entity boxes are drawn as
Soft boxes
Which of the following is true about supertypes and subtypes?
Subtypes inherit the relationships and attributes of the supertype.
Examine the following entity and decide which attribute breaks the 2nd Normal Form rule: ENTITY: CLASS ATTRIBUTES: CLASS ID DURATION SUBJECT TEACHER NAME AND ADDRESS Mark for Review (1) Points CLASS ID SUBJECT TEACHER NAME AND ADDRESS (*) DURATION
TEACHER NAME AND ADDRESS (*)
A/an _________ is a piece of information that in some way describes an entity. It is a property of the entity and it quantifies, qualifies, classifies, or specifies the entity.
Table
Consider the recommended drawing conventions for ERD's. Indicate which of the following accurately describes diagramming conventions for entities and attributes
The * means that an attribute is mandatory or required; the entity name should be singular
Why would you want to model a time component when designing a system that lets people buy bars of gold
The price of gold fluctuates and, to determine the current price, you need to know the time of purchase.
Business rules are important to data modelers because:
They capture all of the needs, processes, and required functionality of the business
Many reasons exist for creating a conceptual model. Choose three appropriate reasons from the options below.
They model functional and informational needs. (*) They capture the implementation details of the physical model. They model the information flow of data. They capture current and future needs. (*) They accurately describe what a physical model will contain. (*)
Which of the following statements about attributes are true?
They must be single valued unless they belong to more than one entity. They have a data type, such as number or character string. (*) They are often adjectives. They describe, qualify, quantify, classify, or specify an entity. (*)
If a relationship can be moved between instances of the entities it connects, it is said to be:
Transferable
A subtype can have a relationship not shared by the supertype. True or False?
True
All attributes that are part of the UID are mandatory. True or False? True (*) False
True
All instances of a subtype must be an instance of the supertype. True or False?
True
All instances of the supertype are also instances of one of the subtypes. True or False?
True
An Entity Relationship model is independent of the hardware or software used for implementation.
True
As a database designer, you have a responsibility to store data in only one place and in the best possible place. True or False? True (*) False
True
If subtypes are listed, a supertype should have at least two subtypes. True or False?
True
In a payroll system, it is desirable to have an entity called DAY with a holiday attribute when you want to track special holidays
True
In the grid computing model, resources are pooled together for efficiency
True
Matrix Diagrams help verify that you have identified all possible relationships between your existing entities
True
Oracle was one of the first relational database systems available commercially. True or False?
True
The purpose of an ERD is to document the proposed system and facilitate discussion and understanding of the requirements captured by the developer
True
Two entities can have one or more relationships between them.
True
Secondary UID's are Mark for Review (1) Points Not permitted in data modeling Useful as an alternative means of identifying instances of an entity (*) Always comprised of numbers Mandatory in data modeling
Useful as an alternative means of identifying instances of an entity
When are relationships unnecessary?
When you can derive the relationship from other relationships in the model
On an ER diagram, which symbol identifies an attribute as part of a unique identifier
#
You are doing a data model for a computer sales company where the price fluctuates on a regular basis. If you want to allow the company to modify the price and keep track of the changes, what is the best way to model this?
Create a product entity and a related price entity with start and end dates, and then let the users enter the new price whenever required. B. Create a new item and a new price every day. C. Use a price entity with a start and end date D. Allow them to delete the item and enter a new one. E. Both A and C (*)
What is the purpose of a Unique Identifier?
Create an entity that is unlike any other entity aside from itself.
What are the major content areas covered in the Oracle Academy?
Data Modeling, SQL, and PL/SQL
Which of the following is a logical constraint that could result from considering how time impacts the storage of data
Dates have value only with a time component. ASSIGNMENT periods can overlap causing the database to crash. End Date must be before the Start Date. An ASSIGNMENT may only refer to a COUNTRY that is valid at the Start Date of the ASSIGNMENT.
All of the following would be instances of the entity PERSON except which
David Jones Angelina Rosalie Grace Abinajam Male (*)
A non-transferable relationship is represented by which of the following symbols?
Diamond
Unique Identifiers
Distinguish one instance of an entity from all other instances of that entity
In a business that sells computers, choose the best relationship name from CUSTOMER to ITEM (computer, in this case
Each CUSTOMER must be the buyer of one or more ITEMS
Changes in computing have affected many of our day-to-day activities. Are all of the following activities examples of this change? Yes or No? In the past you used to use the phone system to call directory assistance to get a phone number. Today you can use your PC to look up a phone number online. In the past you used to have to go to the shoe store to buy shoes. Today you can use your PC to order shoes online. In the past you had to use your PC to send a person an email. Today you can use your phone to send a text message
Yes
If you are tracking employment dates for an employee, do you need to have an "End Date" attribute
Yes, if the company wants to track multiple start dates and insure that multiple employment dates for an employee do not overlap
How would you model a business rule that states that on a student's birthday, he does not have to attend his classes?
You cannot model this. You need to document it
An Entity Relationship Diagram is an example of a Physical Model.
false
A Matrix Diagram will help you with all of the following except
identifying Entities Verifying Relationships Between Entities Naming Relationships Defining Instances of Entities (*)
Which symbol is used to show that a particular attribute is optional
o
