Chapter 3: Databases

Question 1

Database

Answer 1

• A central repository of information, stored more-or-less permanently on a computer system, that is of interest to some enterprise.
• The heart of an information system, is a collection of all relevant facts organized in a series of integrated files (tables)

Question 2

Database Management System (DBMS)

Answer 2

• A generalized software tool for manipulating large databases; it provides minimally the capabilities of interrogation and maintenance of the stored data, via a set of languages or user interfaces.
• Is software for creating, storing, maintaining, and accessing database files
• A software program that lets the user create databases and then manipulate the data in the databases

Question 3

5 Purposes of Database Systems

Answer 3

1. Record and organize data
2. Maintain (create, delete, modify/update) data
3. Interrogation (Questioning/retrieving data)
4. Interconnect data
5. Security, control, data sharing

Question 4

Table =

Answer 4

Relation/Record (Multiple records)

Records make up Fields which makes up a File

Question 5

Row of a table =

Answer 5

Record/Tuple

• Multiple records create a table
• Record = Makes up a field

Question 6

Column of a table =

Answer 6

Field/attributes

• Made up of records
• Group of fields make up a file

Question 7

Files

Answer 7

Database file with multiple tabes (all in the same database) interrelated

Question 8

Primary Key

Answer 8

• Uniquely identifies every record in a database
• Cannot repeat
• Can be foreign key if same field is in another table

Question 9

Foreign Key

Answer 9

Field in a table that matches the primary key column of another table

Question 10

Sequential access file structure

Answer 10

Records in files are organized and processed in numerical or sequential order (usually order in which they were entered)

Question 11

Random access file structure

Answer 11

Records can be accessed in any order

Question 12

Indexed sequential access method (ISAM)

Answer 12

• Records can be accessed sequentially or randomly depending on number being accessed
• Small company: Random
• Large company: Sequential

Question 13

Physical View

Answer 13

• One way that information is viewed in a database
• Involves how data is stored and how its retrieved
• Ex: Hard disks, magnetic tapes, or CDs

Question 14

Logical View

Answer 14

• One way that information is viewed in a database
• Involves how information appears to users and how it can be organized and retrieved
• Usually doesn’t display data (database view)

Question 15

Data Model

Answer 15

• Determines how data is created, represented, organized, and maintained.
• Usually contains data structure, operations, and integrity (quality/accuracy) rules

Question 16

Structured Query Language (SQL)

Answer 16

Standard 4th gen query language that consists of several keywords specifying actions to take
Ex: SELECT field FROM table or file WHERE conditions

Question 17

Query by example (QBE)

Answer 17

• You request data from a database by constructing a statement made up of query forms
• You simply click to select query forms instead of having to remember key words (as with SQL)
• You can add AND (all conditions), OR (one condition), and NOT (no condition) operations to the QBE form to fine-tune the query
• Query = question

Question 18

Relational Model

Answer 18

• Uses a two-dimensional table of rows and columns of data
• Rows are records, also called tuples
• Columns are fields, also called attributes

Question 19

Data dictionary

Answer 19

Stores definitions, such as data types for fields, default values, and validation rules for data in each field

Question 20

Normalization

Answer 20

• Used to improve database efficiency by:
  
  • > Eliminating redundant data
  • > Ensuring that only related data is stored in a table
• Goes through different stages, from first normal form (1NF) to fifth normal form (5NF)

Question 21

Create, read, update, and delete (CRUD)

Answer 21

Refers to the range of functions that data administrators determine who has permission to perform certain functions

Question 22

Database administrators (DBA)

Answer 22

• Design and set up databases
• Establish security measures
• Develop recovery procedures
• Evaluate database performance
• Add/fine-tune database functions
• Used in large organizations

Question 23

Data driven web site

Answer 23

Acts an interface to a database, retrieving data for users and allowing users to enter data in the database

Question 24

Application generation

Answer 24

Design elements of an application using databases

Question 25

Data Administration

Answer 25

Backup and recovery, security, change management

Two types: Create, read, update, and delete (CRUD) and Database administrators (DBA)