Data Base Design Exam 1

Information is best defined as:

Processed data

Birthdates should be stored using DATE or DATETIME rather than text because:

Date types allow correct sorting, filtering, and time calculations, while text creates ambiguity

Data redundancy occurs when:

The same piece of data is held or stored in more than one place

Admissions accepts Alex, but Financial Aid cannot access the Admissions data directly, so a change made in one department is not reflected in another. Which file-based disadvantage does this illustrate?

Data isolation

Data integrity is best described as:

Ensuring that the data in the database is correct and consistent

'Can the employee responsible for finance access detailed data about a student's assignments?' This question raises which file-based disadvantage?

Security problems

Concurrency is defined as:

The ability of the database to allow multiple users access to the same record without adversely affecting transaction processing

The aspect of the real world that a database represents is sometimes called:

The miniworld, or universe of discourse

Which statement reflects the property that a database is designed, built, and populated for a specific purpose?

It has an intended group of users and some preconceived applications those users are interested in

One row of a table is called a:

Record, or tuple

A Database Management System (DBMS) is:

A collection of programs that allows users to create and maintain databases and control access to them

The self-describing nature of a database system means the database contains:

The data, the metadata, and the relationships between tables

Metadata is best defined as:

A description of the data

Program-data independence is possible because:

The structure is stored in the catalog, outside every program, which insulates the programs from the data

A view is best described as:

A subset of the database, or virtual data derived from the database files but not explicitly stored

The feature that allows multiple users to access data at the same time and stops one clerk's save from overwriting another's is called:

Concurrency control

Deliberately storing a student's name in the transcript table so transcripts print quickly is an example of:

Controlled redundancy, which the DBA must then keep consistent

What is the key difference between file permissions and database permissions?

A file gives you the whole file or nothing, while a database grants access column by column

Which situation was given as a case where a DBMS may NOT be worth using?

The data and its uses are simple, well defined, not expected to change, and only one user needs access

When various copies of the same data contain conflicting data, this is ________________ .

data inconsistency

A data model is best described as:

A collection of concepts or notations for describing data, data relationships, data types and data constraints

In a conceptual data model, a real-world object such as a student or a course is called:

An entity

List the four models in order from the HIGHEST level of abstraction to the lowest.

External, conceptual, logical, physical

At the conceptual level, the designer identifies:

What entities exist and how they are related

Which of these belongs to the LOGICAL (internal) model?

Primary keys, foreign keys and column data types

In a CENTRALIZED database system:

The database and DBMS are stored at a single site, though many sites may connect to it

The main disadvantage of a centralized system is:

It is a single point of failure

A HOMOGENEOUS distributed database system is one where:

All sites use the same DBMS software

A HETEROGENEOUS distributed database system is one where:

Different sites may use different DBMS software, with additional common software to support data exchange

Single-user database system

Supports only one user at a time.

Multiuser database system

Supports multiple users concurrently.

Hierarchical data models

A model where there is a root node and each entity can only have one parent. Many to many relations are not possible using this model.

Hierarchical data models

This is the most common model used these days. Data is represented in 2 dimensional tables with tuples and attributes.

Physical model

The physical representation of the database. It includes how the data will be stored and encrypted.

Physical data independence

When you change the physical model, it doesn't affect the conceptual or logical models

Logical data independence

This refers to the ability to change the logical schema without changing the external schema or user view.

Entity relationship diagram (ERD)

A data model describing the database showing tables, attributes and relationships.

What does an aggregate function do?

Takes many rows and returns a single summary value