Midterm Review
In a physical data model, an attribute becomes a _____________.
Column
A non-transferable relationship is represented by which of the following symbols? A) Heart B) Triangle C) Circle D) Diamond
Diamond
If the same relationship is represented twice in an Entity Relationship Model, it is said to be: A) Resourceful B) Removable C) Redundant D) Replicated
Redundant
The text below is an example of what constraint type? The value in the manager_id column of the EMPLOYEES table must match a value in the employee_id column in the EMPLOYEES table.
Referential Integrity
What command will return data from the database to you?
SELECT
The "Arc Implementation" is a synonym for what type of implementation? A) Supertype and Subtype Implementation B) Supertype Implementation C) Cascade Implementation D) Subtype Implementation
Supertype and Subtype Implementation
On an ER diagram, which symbol identifies an attribute as part of a unique identifier A) x B) * C) o D) #
#
When all attributes are single-valued, the database model is said to conform to: A) 2nd Normal Form B) 4th Normal Form C) 3rd Normal Form D) 1st Normal Form
1st Normal Form
Relationships always exist between A) 3 or more attributes B) 3 or more entities C) 2 attributes D) 2 entities (or one entity and itself)
2 entities (or one entity and itself)
In a SELECT clause, what is the result of 2 + 3 * 2?
8
When you resolve a M:M by creating an intersection entity, this new entity will always inherit: A) The UID's from the entities in the original M:M. B) Nothing is inherited from the original entities and relationship. C) A relationship to each entity from the original M:M. D) The attributes of both related entities.
A relationship to each entity from the original M:M
Which of the following is an example of a structural business rule? A) All employees must belong to at least one department B) All overdue payments will have an added 10 % late fee C) All products will have a selling price no less than 30 % greater than wholesale D) Buildings to be purchased by the business must be current with earthquake building code
All employess must belong to at least one department
What is the rule of Second Normal Form? A) All non-UID attributes must be dependent upon the entire UID. B) Some non-UID attributes can be dependent on the entire UID. C) No non-UID attributes can be dependent on any part of the UID. D) None of the above
All non-UID attributes must be dependent upon the entire UID
If an intersection entity is formed that contains no attributes of its own, its uniqueness may be modeled by A) Creating new attributes. B) Barring the relationships to the original entities. C) Placing the UID attributes from the original entities into the intersection entity. D) None of the above.
Barring the relationships to the original entities
How do you turn "data" into "information"? A) By testing it B) By storing it on a server C) By querying it or accessing it D) By storing it in a database
By querying it or accessing it
Column integrity refers to: A) Columns always having values B) Columns always containing positive numbers C) Columns always containing values consistent with the defined data format D) Columns always containing text data less than 255 characters
Columns always containing values consistent with the defined data format
Which of the following would be a logical constraint when modeling time for a country entity? A) Daily traffic patterns must be monitored to determine which countries are overcrowded. B) People have births and deaths in their countries that must be tracked by the system. C) If you are doing a system for France or Germany, you would need security clearance. D) Countries may change their names and/or borders over a period of time.
Countries may change their names and/or borders over a period of time
A relationship can be both recursive and hierachal at the same time. True or False?
False
A table must have a primary key. True or False?
False
Audit trail attributes cannot be placed in the entities they are auditing, they must be placed in separate, new entities, created just for that purpose. True or False?
False
Foreign keys must be null. True or False?
False
Generic models are generally less complex than a specific model. True or False?
False
Historical data should always be kept. True or False?
False
Systems are always just rolled out as soon as the programming phase is finished. No further work is required once the development is finished. True or False?
False
The DESCRIBE command returns all rows from a table. True or False?
False
The DESCRIBE command will return all rows from a table. True or False?
False
In a physical data model, a relationship is represented as a: A) Foreign Key B) Unique Identifier C) Column D) Primary Key
Foreign Key
The transformation from an ER diagram to a physical design involves changing terminology. Relationships in the ER diagram become __________ , and primary unique identifiers become ____________. A) Foreign keys, Mandatory business rules B) Foreign keys, Primary keys C) Primary keys, Foreign keys D) Foreign keys, Optional business rules
Foreign Key, Primary Key
How do you know when to use the different types of time in your design? A) It depends on the functional needs of the system. B) The rules are fixed and should be followed. C) Always model time; you can take it out later if it is not needed. D) You would first determine the existence of the concept of time and map it against the Greenwich Mean Time.
It depends on the functional needs of the system
The text below is an example of what constraint type: The value in the manager_id column of the EMPLOYEES table must match a value in the employee_id column in the EMPLOYEES table.
Referential integrity
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 A) CLASS ID B) DURATION C) SUBJECT D) TEACHER NAME AND ADDRESS
TEACHER NAME AND ADDRESS
In a physical data model, an entity becomes a/an _____________. A) Constraint B) Table C) Column D) Attribute
Table
Why would you want to model a time component when designing a system that lets people buy bars of gold? A) You would not want to model this; it is not important. B) The price of gold fluctuates and, to determine the current price, you need to know the time of purchase. C) Sales people must determine where the gold is coming from. D) The Government of your country might want to be notified of this transaction.
The price of gold fluctuates and, to determine the current price, you need to know the time of purchase
A recursive relationship should not be part of a UID. True or False?
True
In an ERD, it is a good idea to group your entities according to the expected volumes. By grouping high volume entities together, the diagrams could become easier to read. True or False?
True
In the grid computing model, resources are pooled together for efficiency. True or False?
True
Modeling historical data can produce a unique identifier that includes a date. True or False?
True
Oracle was one of the first relational database systems available commercially. True or False?
True
The demand for Information Technology professionals in today's market is increasing.
True
The explanation below is a column integrity constraint. True or False? A column must contain only values consistent with the defined data format of the column.
True
How would you model a business rule that states that on a student's birthday, he does not have to attend his classes? A) Use a supertype B) Use a subtype C) You cannot model this. You need to document it D) Make the attribute Birthdate mandatory
You cannot model this, you need to document it.
An Entity Relationship Diagram is an example of a Physical Model. True or False?
False
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
In a physical data model, a relationship is represented as a combination of: (Choose Two) A) Column B) Primary Key C) Check Constraint or Unique Key D) Foreign Key
Primary Key Foreign Key
The transformation from an ER diagram to a physical design involves changing terminology. Primary Unique Identifiers in the ER diagram become __________ and relationships become ____________.
Primary keys, foreign keys
Which of the following is the best scenario for using supertype/subtype entities: A) A grocery store that gives customers a choice of plastic or paper bags B) An ice cream store that sells ice cream in sugar cones and regular cones C) A pet store that sells small animals that need different sized cages and different food D) A vehicle dealership that sells boats on trailers, cars, and trucks
A vehicle dealership that sells boats on trailers, cars, and trucks.
What is the function of logging or journaling in conceptual data models? A) Allows you to track the history of attribute values, relationships, and/or entire entities B) Creates a fixed time for all events in a data model. C) Represents entities as time in the data model. D) Gives a timestamp to all entities.
Allows you to track the history of attribute values, relationships, and/or entire entities
Which of the following can be added to a relationship? A) A composite attribute B) An attribute C) An optional attribute can be created D) An arc can be assigned
An arc
Which of the following represents the correct sequence of steps in the Database Development Process? A) Analyze, Design, Build B) Build, Analyze, Design C) Design, Build, Analyze D) Analyze, Build, Design
Analyze, Design, Build
Many to many relationships between entities usually hide what? A) Another entity B) Another relationship C) Uniqueness D) More attributes
Another entity
People are not born with "numbers", but a lot of systems assign student numbers, customer IDs, etc.ﾠA shoe has a color, a size, a style, but may not have a descriptive "number". To be able to uniquely and efficiently identify one instance of the entity SHOE, a/an ______________ UID can be created. A) Unrealistic B) Identification C) Artificial D) Structured
Artificial
The word "Volatile" means: A) Changing constantly; unstable B) Static; unlikely to change C) Limited quantity D) Large quantity
Changing constantly; unstable
Which of the following are examples of data vs. information: A) Student age vs. average age of all students in class B) Bank deposit amount vs. total account balance C) Winning time for a race vs. length of race D) Price of a computer vs. total sales of all computers for a company E) A, B, and D
E) A, B, and D
In a business that sells computers, choose the best relationship name from CUSTOMER to ITEM (computer, in this case) A) Each CUSTOMER may be the producer of one or more ITEMS B) Each CUSTOMER must be the seller of one or more ITEMS C) Each CUSTOMER may be the maker of one or more ITEMS D) Each CUSTOMER must be the buyer of one or more ITEMS
Each customer must be the buyer of one or more items.
The explanation below is an example of which constraint type? A primary key must be unique, and no part of the primary key can be null. A) Entity integrity B) Referential integrity C) Column integrity D) User-defined integrity
Entity Integrity
A table must have at least one candidate key, as well as its primary key. True or False?
False
All data models MUST include generic components in order to remain flexible. True or False?
False
An "Arc Implementation" can be done just like any other Relationship - you simply add the required Foreign Keys. True or False?
False
An entity can be on 2nd Normal Form even if it has repeated values. True or False?
False
An entity can only have one UID. True or False?
False
Attributes become tables in a database. True or False?
False
If a primary key is a set of columns then one column must be null. True or False?
False
If a primary key is a set of columns, then one column must be null. True or False?
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?
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?
False
Non-transferable relationships can only be mandatory, not optional. True or False?
False
One or more columns in a primary key can be null. True or False?
False
One-to-One relationships are transformed into Check Constraints in the tables created at either end of that relationship. True or False?
False
System Documentation is developed right at the end once the system has gone live and users have been using it for a little while. You are more likely to get it correct that way. True or False?
False
The Oracle Database can implement a many to many relationship. You simply create two foreign keys between the two tables. True or False?
False
The SQL statement ALTER TABLE EMPLOYEES DELETE COLUMN SALARY is a valid statement. True or False?
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 A) True B) False
False
When reading a relationship between 2 entities, the relationship is only read from left to right. True or False?
False
You must make sure all entities of a proposed system can fit onto one diagram. It is not allowed to break up a data model into more than one diagram. True or False?
False
A business rule such as "All accounts must be paid in full within 10 days of billing" is best enforced by: A) Making the relationship between CUSTOMER and PAYMENT fully mandatory and 1:1 on both sides B) Hiring a programmer to create additional programming code to identify and report accounts past due C) Making the payment attribute mandatory D) Creating a message to be printed on every bill that reminds the customer to pay within ten days
Hiring a programmer to create additional programming code to identify and report accounts past due
What command can be used to create a new row in a table in the database?
INSERT
In a conceptual model, many-to-many relationships are resolved via a structure called a/an: ________________ - Supertype - Intersection Table - Intersection Entity - Subtype
Intersection Entity
Why is it important to identify and document business rules? A) It allows you to create your data model and then check it for accuracy B) It allows you to improve the client's business C) It ensures that the data model will automate all manual processes D) None of the above
It allows you to create your data model and then check it for accuracy
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" A) Many to Many Mandatory B) One to Many Optional C) One to Many Mandatory D) Many to Many Optional
Many to Many Mandatory
What are the three properties that every relationship should have? A) Name, optionality, arcs B) A UID bar, a diamond, an arc C) Name, optionality, cardinality D) Transferability, degree, name
Name, optionality, cardinality
When data is stored in more than one place in a database, the database violates the rules of ___________. A) Decency B) Normalcy C) Normalization D) Replication
Normalization
A customized hat sitting on your friend's head is an example of which model--the conceptual model or the physical model? - Conceptual Model - Physical Model
Physical Model
If a relationship can be moved between instances of the entities it connects, it is said to be: A) Recursive B) Transferable C) Committed D) Implicit
Transferable
All attributes that are part of the UID are mandatory. True or False?
True
An Entity Relationship model is independent of the hardware or software used for implementation. True or False?
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
Attributes become columns in a database table. True or False?
True
When mapping supertypes, relationships at the supertype level transform as usual. Relationships at the subtype level are implemented as foreign keys, but the foreign key columns all become optional. True or False?
True
The transformation from an ER diagram to a physical design involves changing terminology. Secondary Unique Identifiers become Columns Table Unique Constraints Primary Key Constraints
Unique Constraints
Secondary UID's are: A) Always comprised of numbers B) Mandatory in data modeling C) Useful as an alternative means of identifying instances of an entity D) Not permitted in data modeling
Useful as an alternative means of identifying instances of an entity
The explanation below is an example of which constraint type? If the value in the balance column of the ACCOUNTS table is below 100, we must send a letter to the account owner which will require extra programming to enforce. A) Entity integrity B) Referential integrity C) Column integrity D) User-defined integrity
User-defined Integrity
The text below is an example of what constraint type? If the number of BOOKS lent to a BORROWER in the LIBRARY exceeds 5, then we must send him a letter requesting the return of the BOOKS; this will require extra programming to enforce. - Entity integrity - User-defined integrity - Column integrity - Referential integrity
User-defined Integrity
When are relationships unnecessary? A) When the relationships connect 2 entities and they each have distinct meanings B) When the information does not relate to the model C) When they have the same visual structure but different meaning D) When you can derive the relationship from other relationships in the model
When you can derive the relationship from other relationships in the model
