Database Midterm
Identifying relationship (Modeling)
A double line connecting two entities represents a ________
7560000
A fact table has 4 corresponding dimension tables. The dimension tables have 20, 35, 90 and 120 records successively. The fact table will have ______ entries. (answer in numeric form with no comma separators)
curly brackets
A multi-valued attribute is represented by _____ ______.
attribute
A property or characteristic of an entity type that is of interest to the organization is called a(n):
Associative Entity (Modeling)
A rectangle with rounded corners represents a ____
Strong Entity (Modeling)
A regular rectangle represents a ____
Weak Entity (Modeling)
A regular rectangle with double line sides represents a ___ ____.
False. (If the relation has a composite primary key doesn't mean it will have partial dependencies)
A relation which has a composite primary key is necessarily in 1 NF form as it will have Partial Dependencies
True
A subtype inherits the attributes as well as the relationships of a supertype. T/F
True
An Entity Type in an ER model becomes a Relation in the Logical model.
weak entity
An entity that displays existence dependence and inherits the primary key of its parent entity. For example, a DEPENDENT requires the existence of an EMPLOYEE.
strong entity (Definition)
An entity that is existence-independent, that is, it can exist apart from all of its related entities. Also called a regular entity.
Associative Entity (Definition)
An entity type that associates the instances of one or more entity types and contains attributes that are peculiar to the relationship between those entity instances.
False (Always is a strong word)
Data in a BIS - Business Information System is always normalized.
Metadata
Data that describes the properties of other data are:
False (Many to Many relationships ALWAYS create an associative entity)
Depending on business rules, many-to-many relationships may or may not create an Associative Entity between them.
square brackets
Derived attributes are represented by _____ _____.
conceptual
Different user views are consolidated into a ______ schema.
Source System
During Data Scrubbing and Cleansing, the errors are always fixed in which system?
False
Entity types represent a collection of entity instances and are hence named as plural nouns.
bold and underlined
Identifiers are represented as ____ and ____ in E-R diagrams.
False (The finest possible grain is a click)
In E-commerce, the finest possible grain is a transaction. T/F
Regular Brackets
Individual attributes that make up a composite attribute are enclosed within _____ _____.
Generalization
Modeling data by finding Subtype first and then defining the supertype (BOTTOM UP)
Specialization
Modeling data by findingSupertype first and then defining the subtype (TOP DOWN)
True
Relationships are represented by a verb phrase. T/F
False (Removing Transitive Dependencies is 2NF to 3NF)
Removing partial dependency converts a relation to the 3rd normal form. T/F
True
Removing transitive dependencies convert a relation from the 2NF to the 3NF.
False
Since data always represents one version of truth, a company can have one and only one external schema. T/F
False (The primary keys of a fact key come from a dimension table, not vice versa as stated in the question)
The Dimension Table is nothing but an Associative Entity Type and has its primary key consisting of the primary keys of the different Fact Tables. T/F
False. The EDW is fed with data using only one load process.
The EDW - Enterprise Data Warehouse system is fed with data using several Load processes that are customized for each of the individual Data Marts
Identifying relationship (Definition)
The relationship between a weak entity type and its owner
True
To convert a multi-valued attribute in an entity type to a relation, the rule is to create a separate entity type for the multivalued attribute and create an identifying relationship between them.
True
When creating the logical model for a supertype-subtype relationship, every subtype's primary key is the same as the primary key of the supertype. T/F
True
When the constraint says that in a relation, every attribute value must be atomic, it means that multivalued and composite attributes of an entity type are not allowed in a relation.
Disjointness Constraints
Whether an instance of a supertype may simultaneously be a member of two (or more) subtypes
Completeness Constraints
Whether an instance of a supertype must also be a member of at least one subtype
The primary Key from Vendor, i.e. Vendor_ID is transferred to Material and becomes the Foreign Key in the Material relation. This is a one-to-many relationship from the Vendor to Material. In a one-to-many relationship, the PK from the side of the one is transferred to the relation on the "many" side and becomes the FK.So, in this case, the primary Key from Vendor, i.e. Vendor_ID is transferred to Material and becomes the Foreign Key in the Material relation.
Your company has a very strict vendor evaluation and approval process. It has dedicated suppliers for each material it buys. One material can have one and only one supplier. A supplier however can supply one or many materials for which it has received approval. When you model this, which relation gets the foreign key for which relation?
