Exam 2
True
A candidate key is an attribute, or combination of attributes, that uniquely identifies a row in a relation
1. the key must uniquely identify the row 2. the key must be nonredundant 3. each nonkey attribute is functionally dependent upon it
A candidate key must satisfy all of the following conditions
Integrity Constraints
A domain definition consists of the following components EXCEPT
True
A partial functional dependency is a functional dependency in which one or more nonkey attributes are functionally dependent on part (but not all) of the primary key.
True
A range control limits the set of permissible values that a field may assume
True
A referential integrity constraint is a rule that maintains consistency among the rows of two relations
False
A relation is in first normal form if it has no more than one multivalued attribute
Second Normal Form
A relation that contains no multivalued attributes and has nonkey attributes solely dependent on the primary key but contains transitive dependencies is in which normal form?
Referential Integrity Constraint
A rule that states that each foreign key value must match a primary key value in the other relation is called the
False
A transversal dependency is a functional dependency between two or more nonkey attributes
True
A well-structured relation contains minimal redundancy and allows users to manipulate the relation without errors or inconsistencies.
Pointer
A(n) ________ is a field of data used to locate a related field or record
A one-to-many relationship
All of the following are common denormalization opportunities EXCEPT
use a lot of storage space
All of the following are objectives when selecting a data type EXCEPT
Boolean
All of the following are valid datatypes in Oracle 11g EXCEPT
True
All values that appear in a column of a relation must be taken from the same domain
Efficiency
An advantage of partitioning is
False
An anomaly is a type of flaw in the database server
Range Control
An integrity control supported by a DBMS is
False
Anomalies do not generally arise out of transitive dependencies
True
Clustering allows for adjacent secondary memory locations to contain rows from several tables.
Transaction Volumes
Database access frequencies are estimated from
False
Denormalization is the process of transforming relations with variable-length fields into those with fixed-length fields
Horizontal Partitioning
Distributing the rows of data into separate files is called
Checking to see if missing data will greatly impact results
Sensitivity testing involves
Default Value
The value a field will assume unless the user enters an explicit value for an instance of that field is called a(n):
you must be able to check the output of a CASE tool.
Understanding the steps involved in transforming EER diagrams into relations is important because
False
Unlike columns, the rows of a relation may not be interchanged and must be stored in one sequence
False
When transforming a unary many-to-many relationship to relations, a recursive foreign key is used
False
When transforming a weak entity, one should create one relation with both the attributes of the strong entity and the attributes of the weak entity
True
A cascading delete removes all records in other tables associated with the record to be deleted
1. Fast data retrieval 2. security 3. efficient storage
A factor to consider when choosing a file organization is
False
A file organization is a named portion of primary memory
True
A foreign key is a primary key of a relation that also is a primary key in another relation.
Physical
A form of database specification that indicates all the parameters for data storage that are then input to database implementation is
Transitive Dependency
A functional dependency between two or more nonkey attributes is called a
False
A key is a data structure used to determine the location of rows in a file that satisfy some condition
1. substitute and estimate for the missing data 2. track missing data with special reports 3. perform sensitivity testing
A method for handling missing data is to
1. normalized relations 2. definitions of each attribute 3. technology descriptions
A requirement to begin designing physical files and databases is
when different categories of a table's rows are processed separately
Horizontal partitioning makes sense when
True
If an identifier is not assigned, the default primary key for an associative relation consists of the two primary key attributes from the other two relations.
False
In the relational data model, associations between tables are defined through the use of primary keys
False
Indexes are most useful on small, clustered files
True
Keeping the zip code with the city and state in a table is a typical form of denormalization
1. minimize data redundancy 2. simplify the enforcement of referential integrity 3.make it easier to maintain data
Main goals of Normalization
Data Accessibility, Response Time & Security
Physical database design decisions must be made carefully because of impacts on
False
Reduced uptime is a disadvantage of partitioning.
True
Security is one advantage of partitioning
Entity Integrity Rule
The ________ states that no primary key attribute may be null
True
The allowable range of values for a given attribute is part of the domain constraint
Determinant
The attribute on the left-hand side of the arrow in a functional dependency is the
True
The columns of a relation can be interchanged without changing the meaning or use of the relation
no primary key attribute can be null
The entity integrity rule states that
False
The entity integrity rule states that a primary key attribute can be null
Data Structure, Data Manipulation & Data Integrity
The relational data model consists of which components?
Field
The smallest unit of application data recognized by system software is a
First Normal Form
When all multivalued attributes have been removed from a relation, it is said to be in
True
When normalizing, the goal is to decompose relations with anomalies to produce smaller, well-structured relations
False
When transforming a one-to-one relationship, a new relation is always created
1. Each attribute has a unique name 2.No two rows in a relation are identical 3.There are no multivalued attributes in a relation
Which of the following are properties of relations?
Improve Data Integrity
Which of the following is an objective of selecting a data type
operating system
While Oracle has responsibility for managing data inside a tablespace, the tablespace as a whole is managed by the
Data Integrity
________ is a component of the relational data model included to specify business rules to maintain the integrity of data when they are manipulated.