Chapter 1: Introduction

Question 1

What is a Database

Answer 1

A massive software

Question 2

When asked, “What is better, X or Y?” what should your answer be

Answer 2

It depends because of how massive DB is

Question 3

What is OLTP

Answer 3

Online Transaction Processing

Question 4

What does OLTP do

Answer 4

tracks transaction changes in a system. this involves lots of writing to the system, causing many changes to the DB

Question 5

What does OLTP try to minimize

Answer 5

OLTP tries to minimize the number of writes done because writing to the system takes a lot of time.

Question 6

What is OLAP

Answer 6

Online Analytic Processing

Question 7

What does OLAP do

Answer 7

OLAP reads and analyzes from the DB. It is read oriented and makes very few changes to the DB.

Question 8

What is the purpose of Schema?

Answer 8

Schema make up the logical structure of the DB. They structure the DB and determine how the data is stored, just like what classes do in programs.

Question 9

What is the purpose of Instances?

Answer 9

Instances are the actual contents of the DB at a particular point in time. They are analogous to variables in programs.

Question 10

What is a Data Model?

Answer 10

Data models describe data, data relationships, data semantics, and data constraints (rules). They range from laymen to technical and human oriented to machine oriented. All data models are functionally equivalent to each other.

Question 11

What types of Data Models are there?

Answer 11

• Entity-Relationship data model (for laymen and database design)
• Relational model (mathematical)
• Relational DB (technical)

Question 12

What are the languages for the Data Models?

Answer 12

• ER (Entity Relationship Model) Language: GUI, Diagrams
• Relational model: Relational Algebra (procedural language)
• RDB Language: SQL (Declarative language)

Question 13

What is a DML?

Answer 13

Data Manipulation Language. A language for accessing and manipulating the data organized by the appropriate data model (aka query language)

Question 14

What classes of DML languages are there?

Answer 14

• Procedural: user specifies what data is required and how to get that data (I want x so go here and …)
• Declarative: user specifies what data is required without specifying how to get it (I want this)

Question 15

What is a DDL?

Answer 15

Data definition language.

• notation for defining database schema
• comprised of database schema, integrity constraints, and authorization

Question 16

What is the differences between DDLs and DMLs?

Answer 16

• DDL: operates on schema and the structure of the DB (like types in a program)
• DML: operates on the contents/instances (like variables)

Question 17

What is the difference between declarative languages and procedural languages?

Answer 17

declarative languages you declare WHAT you want, and procedural languages you describe HOW to get what you want

Question 18

In an Entity-Relationship model what are the terms for a “thing”, “a set of things”, and “essential characteristics”?

Answer 18

• “thing” = entity
• “a set of things” = entity set (or relationship set)
• “essential characteristics” = attributes

Question 19

In an Relational model what are the terms for a “thing”, “a set of things”, and “essential characteristics”?

Answer 19

• “thing” = tuple
• “a set of things” = relation
• “essential characteristics” = attributes

Question 20

In an Relational Database model what are the terms for a “thing”, “a set of things”, and “essential characteristics”?

Answer 20

• “thing” = row
• “a set of things” = table
• “essential characteristics” = columns

Question 21

What is a Relational Database?

Answer 21

A databse based on the relational data model. Is represented by a collection of tables and includes DML and DDL.

Question 22

What makes Relational Databases such powerful tools?

Answer 22

• simple representations of data (everything is a table)

- separates the WHAT (SQL) from the HOW (relational algebra)