Mid term practice Flashcards
(17 cards)
An ERD is a pictorial representation of
Users data
A reverse engineered ERD from a relational database is always a
Physical ERD
An attribute that cannot be broken into smaller components is called
Atomic Attribute
The number of entities that participate in a relationship is called
Degree
Select two options - An entity should not be
A report
A concept
An event
A user of the system
A place
A report, A user of the system
What is a composite attribute?
An attribute can be further subdivided into meaningful parts
5 items that Metadata should have
-Data types
-Source
-Description of data
-Name of attribute
-Constraints
A drug has contraindications with another drug, i.e. a drug cannot be taken with another drug. What type of a degree is best suited to represent such a relation.
Unary
A data administrator decides to store the street number, street name, city, province and postal code, all in a single address field, what is such an attribute called:
Composite attribute
A summary that tells the reader about the project and what the reader should expect from the document.
An Abstract
A database engineer using a modeling tool to create an ERD and then uses the tool to create DDL statements. This process is called
Forward Engineering
Often DDL statements are written manually by a database designer. He uses a modeling tool to draw an ERD from this set of DDL statements, this process is called
Reverse Engineering
An association between one, two or three entities is called
A relationship
A table has a composite key and repeating data items have been resolved.
Question options:
The table can never be in second normal form, it will always have partial functional dependency because it has a composite key
The table may be in first, second or third normal form based on rules.
The table can never be in second normal form unless the composite key is resolved into a primary key that have only one attribute.
The table may be in first, second, or third normal form
Some data needs to be deleted from a table. Other relevant data is lost in the delete operation. What is this called?
Deletion Anomaly
Data needs to be added to a table. Two situations arise
- The user is forced to add data to other fields that are in the table.
- Data is not available for all fields, the user is forced to add NULL values to other fields .
What is this called?
Insertion Anomaly
Identify the rule that maintains consistency among the rows of two relations
Referential Integrity Rule
