Chapter 1

Question 1

Database-Management System (DBMS)

Answer 1

A collection of interrelated data and a set of programs to access those data

Question 2

Five disadvantages of file processing systems:

Answer 2

1. Redundancy & inconsistency
2. Difficulty in access
3. Data isolation
4. Atomic problems
5. Integrity problems

Question 3

File processing systems problems: data redundancy & inconsistency

Answer 3

Data is stored multiple times and in different structures, sometimes not up to date

Question 4

File processing systems problems: difficulty in access

Answer 4

Programs might not exist to access data in a desirable manner

Question 5

File processing systems problems: data isolation

Answer 5

Data is sometimes scattered across files, therefore hard to access

Question 6

File processing systems problems: atomicity problems

Answer 6

Data must be processed at once, in order to ensure a correct processing

Question 7

File processing systems problems: integrity problems

Answer 7

Its hard to implement new constraints to data

Question 8

Three kinds of data models

Answer 8

1. Relational model: tables, record based, fixed format
2. Entity-relationshop model: data stored in objects or entities
3. Semi-structured data: XML or JSON, dictionaries/lexicons

Question 9

Three levels of database organization

Answer 9

1. Physical schema: the physical storing of data
2. Logical schema: what data is stored and what’s the relation to other data
3. View level: representation of data, subschemas

Question 10

Instance

Answer 10

Collection of certain data at certain moment

Question 11

DDL & DML

Answer 11

data-definition language & data-manipulation language

Question 12

DDL has three required constraints

Answer 12

1. Domain constraints
2. Referential integrity
3. Authorization

Question 13

DDL constraint: domain constraints

Answer 13

A domain of possible values must be associated with every attribute

Question 14

DDL constraint: referential integrity

Answer 14

Some data must be relational to data in another relation in order to make sense, for referential integrity

Question 15

DDL constraint: authorization

Answer 15

Four levels of authorization we may want to give a user:
1. Read authorization
2. Insert authorization
3. Update authorization
4. Delete authorization

Question 16

Difference between procedural DMLs and declarative DMLs

Answer 16

Procedural DMLs require a user to specify what data is needed and where to get it, whereas declarative DMLs doesn’t need the specification of where to get the data from

Question 17

Application program

Answer 17

Program that accesses interacts with databases

Question 18

Five phases of database design

Answer 18

1. Specification of user requirements
2. Conceptual design phase
3. How to implement: employ a set of algorithms
4. Logical design phase
5. Physical design phase