Database Concepts Test 2

Dr Edgar F. Codd, after his extensive research on the Relational Model of database systems, came up with rules a database must obey in order to be regarded as a true relational database. How many are there?

12

Comprehensive Data Sub-Language Rule

A database can only be accessed using a language having linear syntax that supports data definition, data manipulation, and transaction management operations

Integrity Independence

A database must be independent of the application that uses it

High-Level Insert, Update, and Delete Rule

A database must support insertion, updation, and deletion by row, union, intersection, and minus operations

How is a relation instance defined?

A finite set of tuples in the relational database system

How is a relation schema defined?

A relation schema describes the relation name (table name), attributes, and their names

In a relational data model what is a tuple?

A single row

Regarding the mapping process of hierarchical entities, which of the following are included? Select all that apply.

Add primary keys of higher-level entities in the table of lower-level entities Create tables for all higher-level entities Declare primary key of higher-level table and the primary key for lower-level table

Which of the following are part of the Mapping Relationship process? Select all that apply.

Add the primary keys of all participating Entities as fields of table with their respective data types Declare a primary key composing all the primary keys of participating entities

View Updating Rule

All the views of a database, which can theoretically be updated, must also be updatable by the system

The SQL Data Definition Language uses which of the following set of commands to define database schema? Select all that apply.

Alter Create Drop

Which of the following are part of the Mapping Entity process? Select all that apply.

Create table for each entity Declare primary key

What do ER diagrams mainly comprise of? Select all that apply.

Entity attributes, Entities, Association among entities, and Relationships

Domain Constraints

Every attribute is bound to have a specific range of values

Guaranteed Access Rule

Every single data element is guaranteed to be accessible logically with a combination of table-name, primary key, and

Information Rule

Everything in a database must be stored in a table format

The WHERE clause does not define predicate or conditions, which must match in order to qualify the attributes to be projected.

False

Non-Subversion

If a system has an interface that provides access to low-level records, then the interface must not be able to subvert the records

The SQL Data Manipulation Language uses which of the following set of commands to modify the database instance? Select all that apply

Insert Update Delete

Candidate Keys

More than one such minimal subsets of attributes

Systematic Treatment of NULL Values

NULL values in a database must be given a systematic and uniform treatment

Physical Data Independence

The data stored in a database must be independent of the applications that access the database.

Distribution Independence

The end-user must not be able to see that the data is distributed across various locations

Logical Data Independence

The logical data stored in a database must be independent of its user's view

Active Online Catalog

The structure description of the entire database must be stored as a data dictionary

ER Model, when conceptualized into diagrams, gives a good overview of entity-relationship.

True

It is possible to create relational schema using ER diagram

True

SELECT is one of the fundamental query commands of SQL.

True

The FROM clause takes a relation name as an argument from which attributes are to be selected/projected.

True

We cannot import all the ER constraints into relational model, but an approximate schema can be generated.

True

Regarding inheritance, when the details of entities are generally hidden from the user, what is this known as?

abstraction

Insert Into/Values

for inserting values into the rows of tables (relation)

At UCF, everyone associated with the university is a Person. Each Person has a specific role they fulfill, Student, Faculty, Staff, and Maintenance. Based on the fact that the ER Model has the power of expressing database entities in a conceptual hierarchical manner, referencing Person, what would the entity be considered as?

generalization

The ER Model has the power of expressing database entities in a conceptual hierarchical manner. Going up in this structure is called what?

generalization

Referential integrity constraints

if a relation refers to a key attribute of a different or same relation, then that key element must exist

When using inheritance, which of the following is true?

lower-level entities to inherit the attributes of higher-level entities

Key

one minimal subset of attributes in the relation, which can identify a tuple uniquely

What is a relation key?

one or more attributes which can identify the tuple in the relation uniquely

What is the definition of a weak entity set?

one which does not have any primary key associated with it

Delete/From/

removing one or more rows from a table(relation)

What is the attribute domain?

some pre-defined value scope

At UCF, everyone associated with the university is a Person. Each Person has a specific role they fulfill, Student, Faculty, Staff, and Maintenance. Based on the fact that the ER Model has the power of expressing database entities in a conceptual hierarchical manner, referencing Student, what would the entity be considered as?

specialization

The ER Model has the power of expressing database entities in a conceptual hierarchical manner. Entities divided into sub-groups based on their characteristics is called what?

specialization

What is the format are relations saved in a relational data model?

tables

Update/Set/Where

updating or modifying the values of columns of tables(relation)