CIS275 - Chapter 1: Introduction to Databases

Question 1

Numeric, textual, visual, or audio information that describes real-world systems.

Answer 1

Data

Question 2

The variance in the amount of data produced and collected. Ex: A small business might track an inventory of a few thousand items, but a large commerce website might track billions of items.

Answer 2

Scope

Question 3

The manner data may be produced (i.e. numbers, text, image, audio, or video). Ex: A phone’s proximity sensor generates raw numbers, and a satellite captures images.

Answer 3

Format

Question 4

The level of availability of a data source and who it is available to. Ex: A retail company may use private customer data to discover purchasing behavior patterns, but a government may be required by law to share certain data sets.

Answer 4

Access

Question 5

Historically, data was mostly ____, encoded as continuous variations on various physical media. Ex: Audio was recorded as vibrations impressed on vinyl disks. Images were recorded as chemicals on celluloid tapes.

Answer 5

analog

Question 6

Today, data is mostly _____, encoded as zeros and ones on electronic and magnetic media.

The shift from analog to ____ data facilitated the rise of large computer databases.

Answer 6

digital

Question 7

A collection of data in a structured format.

Answer 7

database

Question 8

Software that reads and writes data in a database.

Answer 8

database system (database management system or DBMS)

Database systems ensure data is secure, internally consistent, and available at all times. These functions are challenging for large databases with many users, so database systems are complex.

Question 9

A specialized programming language, designed specifically for database systems.

Answer 9

query language

Query languages read and write data efficiently, and differ significantly from general-purpose languages such as Python, Java, and C++.

Question 10

Software that helps business users interact with database systems.

Answer 10

database application

Many databases are complex, and most users are not familiar with query languages. Consequently, direct database access is usually not feasible. Instead, programmers write applications to simplify the user experience and ensure data access is efficient and secure.

Database software is organized in layers. Applications interact with a query language on one layer, and a query language interacts with a database system on another layer. Other software layers, such as the operating system, are beyond the scope of this material.

Question 11

A _____ is responsible for securing the database system against unauthorized users. A _____ enforces procedures for user access and database system availability.

Answer 11

database administrator

Question 12

A _____ determines the format of each data element and the overall database structure. _____ must balance several priorities, including storage, response time, and support for rules that govern the data. Since these priorities often conflict, _____ is technically challenging.

Answer 12

database designer

Question 13

A _____ develops computer programs that utilize a database. _____ write applications that combine database query languages and general-purpose programming languages. Query languages and general-purpose languages have significant differences, so _____ is a specialized challenge.

(same role in all 3 gaps)

Answer 13

database programmer

Question 14

A _____ is a consumer of data in a database. _____ request, update, or use stored data to generate reports or information. _____ usually access the database via applications but can also submit queries directly to the database system.

(same role in all 3 gaps)

Answer 14

database user

Question 15

Answer 15

Question 16

Answer 16

Question 17

Large, complex databases that are shared by many users have special requirements:

Answer 17

Performance. When many users and applications simultaneously access large databases, query response time degrades rapidly. Database systems must maintain fast response times by structuring data properly on storage media and processing queries efficiently.

Authorization. Many database users should have limited access to specific tables, columns, or rows of a database. Database systems must authorize individual users to access specific data.

Security. Database systems must ensure authorized users only access permissible data. Database systems must also protect against hackers by encrypting data and restricting access.

Rules. Database systems must ensure data is consistent with structural and business rules. Ex: When multiple copies of data are stored in different locations, copies must be synchronized as data is updated. Ex: When a course number appears in a student registration record, the course must exist in the course catalog.

Recovery. Computers, database systems, and individual transactions occasionally fail. Database systems must recover from failures and restore the database to a consistent state without loss of data.

Question 18

A group of queries that must be either completed or rejected as a whole.

Answer 18

A transaction

Execution of some, but not all, queries results in inconsistent or incorrect data. Ex: A debit-credit transaction transfers funds from one bank account to another. The first query removes $100 from one account and the second query deposits $100 in another account. If the first query succeeds but the second fails, $100 is mysteriously lost. The transaction must process either both queries or neither query.

Question 19

When processing transactions, database systems must:

Answer 19

Ensure transactions are processed completely or not at all.

Prevent conflicts between concurrent transactions.

Ensure transaction results are never lost.

Question 20

Answer 20

Question 21

The _____ of a database system describes the internal components and the relationships between components.

Answer 21

architecture

Question 22

The _____ interprets queries, creates a plan to modify the database or retrieve data, and returns query results to the application. The _____ performs query optimization to ensure the most efficient instructions are executed on the data.

Answer 22

query processor

Question 23

The _____ translates the query processor instructions into low-level file-system commands that modify or retrieve data. Database sizes range from megabytes to many terabytes, so the _______ uses indexes to quickly locate data.

Answer 23

storage manager

Question 24

The _____ ensures transactions are properly executed. The _____ prevents conflicts between concurrent transactions. The _____ also restores the database to a consistent state in the event of a transaction or system failure.

Answer 24

transaction manager

Question 25

The ___ is a file containing a complete record of all queries processed by the database. The transaction manager writes ___ records before applying changes to the database. In the event of a failure, the transaction manager uses ___ records to restore the database.

Answer 25

log

Question 26

The \_\_\_\_\_, also known as a data dictionary, is a directory of tables, columns, indexes, and other database objects. Other components use _____ information to process and execute queries.

Answer 26

catalog

Question 27

Answer 27

Question 28

A _____ stores data in tables, columns, and rows, similar to a spreadsheet.

Answer 28

relational database All data in a column has the same format. All data in a row represents a single object, such as a person, place, product, or activity.

Question 29

All relational database systems support the SQL query language. SQL stands for _____ and includes statements that read and write data, create and delete tables, and administer the database system.

Answer 29

Structured Query Language

Question 30

The growth of the internet in the 1990s generated massive volumes of online data, called \_\_\_\_\_, often with poorly structured or missing information.

Answer 30

big data

Question 31

The newer non-relational systems are called \_\_\_\_\_, for 'not only SQL', and are optimized for big data.

Answer 31

NoSQL

Question 32

\_\_\_\_\_ software is software that anyone can inspect, copy, and modify with no licensing fee.

Answer 32

Open source

Question 33

A command for a database that typically inserts new data, retrieves data, updates data, or deletes data from a database.

Answer 33

query

Question 34

A computer programming language for writing database queries.

Answer 34

query language

Question 35

The four common queries are sometimes referred to as CRUD operations, an acronym for:

Answer 35

Create, Read, Update, and Delete data.

Question 36

The standard query language of relational database systems.

Answer 36

Structured Query Language, or SQL

Question 37

A database command, such as a query that inserts, retrieves, updates, or deletes data:

Answer 37

SQL **statement**

Question 38

SQL statement: inserts rows into a table.

Answer 38

INSERT

Question 39

SQL statement: retrieves data from a table.

Answer 39

SELECT

Question 40

SQL statement: modifies data in a table.

Answer 40

UPDATE

Question 41

SQL statement: deletes rows from a table.

Answer 41

DELETE

Question 42

Answer 42

Question 43

The SQL **\_\_\_\_\_** statement creates a new table by specifying the table and column names.

Answer 43

**CREATE TABLE** Each column is assigned a data type that indicates the format of column values. Data types can be numeric, textual, or complex.

Question 44

SQL CREATE TABLE statement data type: stores integer values.

Answer 44

INT

Question 45

SQL CREATE TABLE statement data type: stores fractional numeric values.

Answer 45

DECIMAL

Question 46

SQL CREATE TABLE statement data type: stores textual values.

Answer 46

VARCHAR

Question 47

SQL CREATE TABLE statement data type: stores year, month, and day.

Answer 47

DATE

Question 48

A specification of database objects such as tables, columns, data types, and indexes. _____ also refers to the process used to develop the specification.

Answer 48

Database design

Question 49

For small, simple databases, the database design process can be informal and unstructured. For large, complex databases, the process has three phases:

Answer 49

1. Analysis 2. Logical design 3. Physical design

Question 50

The _____ phase specifies database requirements without regard to a specific database system.

Answer 50

analysis Requirements are represented as entities, relationships, and attributes. Analysis has many alternative names, such as conceptual design, entity-relationship modeling, and requirements definition.

Question 51

An _____ is a person, place, activity, or thing.

Answer 51

entity

Question 52

A _____ is a link between entities.

Answer 52

relationship

Question 53

An _____ is a descriptive property of an entity.

Answer 53

attribute

Question 54

Entities, relationships, and attributes are depicted in \_\_\_\_\_:

Answer 54

ER diagrams ## Footnote Rectangles represent entities. Entity names appear at the top of rectangles. Lines between rectangles represent relationships. Text inside rectangles and below entity names represent attributes.

Question 55

Answer 55

Question 56

The _____ phase implements database requirements in a specific database system.

Answer 56

logical design For relational database systems, logical design converts entities, relationships, and attributes into tables, keys, and columns.

Question 57

A ___ is a column used to identify individual rows of a table.

Answer 57

key

Question 58

The logical design is depicted in a \_\_\_\_\_.

Answer 58

table diagram Table diagrams are similar to ER diagrams but more detailed: Rectangles represent tables. Table names appear at the top of rectangles. Text within rectangles and below table names represents columns. Solid bullets (●) indicate key columns. Empty bullets (○) and arrows indicate columns that refer to keys.

Question 59

The logical design specified in SQL and depicted in a table diagram is called a \_\_\_\_\_.

Answer 59

database schema

Question 60

Answer 60

Question 61

The _____ phase adds indexes and specifies how tables are organized on storage media.

Answer 61

physical design Ex: Rows of a table may be sorted on the values of a column and stored in sort order.

Question 62

In relational databases, logical and physical design affect queries differently. Logical design affects the query result. Physical design affects query processing speed but never affects the query result. The principle that physical design never affects query results is called \_\_\_\_\_.

Answer 62

data independence Data independence allows database designers to tune query performance without changes to application programs. When database designers modify indexes or row order, applications run faster or slower but always generate the same results.

Question 63

Answer 63

Question 64

An _____ is a library of procedures or classes that links a host programming language to a database.

Answer 64

application programming interface (API) The host language calls library procedures, which handle details such as connecting to the database, executing queries, and returning results. Ex: JDBC is a library of Java classes that access relational databases.