Basics DB

Question 1

DBMS

Answer 1

DB + collection of programs to access DB

Question 2

WHY DBMS?

Answer 2

Data redundancy and inconsistency, Difficulty in accessing data, Data isolation, Integrity problems, Atomicity, Concurrent access, Security problems

Question 3

Data redundancy and inconsistency

Answer 3

With file system, same data stored at many places, if we change data at one place but not others, data becomes inconsistent.

Question 4

Difficulty in accessing data

Answer 4

Due to the use of big programs.

Question 5

Integrity constraint problems

Answer 5

Age cannot be negative

Question 6

Atomicity

Answer 6

If one change made then all should follow otherwise rollback , not possible in FS

Question 7

Concurrent access

Answer 7

Multiple people accessing same data

Question 8

Security problems

Answer 8

Authorized access

Question 9

View of data

Answer 9

Physical, logical, view

Question 10

Logical level

Answer 10

Tables of DB, columns, etc.

Question 11

View level

Answer 11

UI level

Question 12

Physical level

Answer 12

Where data actually stored in disk

Question 13

Committ

Answer 13

Save the changes made by transaction

Question 14

Rollback

Answer 14

undo the changes done by transaction

Question 15

Automatic rollback is

Answer 15

Atomicity

Question 16

NULL

Answer 16

Representation of no value

Question 17

DB Languages

Answer 17

DDL, DML

Question 18

DDL

Answer 18

Creation/deletion of tables, adding/deleting cols., changing col. names

Question 19

DML

Answer 19

Inserting/deleting/updating rows, Select

Question 20

DB languages

Answer 20

Procedural and non procedural

Question 21

Procedural

Answer 21

what data and how to get those data

Question 22

Non procedural

Answer 22

what data and not how to get those data. eg. SQL

Question 23

DB users

Answer 23

Naive users(who interact using GUI), application programmers(who access DB while dev), Sophisticated users(who write queries), Specialized users(who create DBMS tools), DBA(manage data at physical/logical/view level)

Question 24

DB system structure

Answer 24

Storage manager, Query processor components

Question 25

DATA MODELS

Answer 25

ER and relational, network, hierarichal, Object oriented

Question 26

ER model

Answer 26

contains entities, relationships

Question 27

Relational model

Answer 27

uses tables

Question 28

DB design

Answer 28

Requirement analysis, conceptual designing using ER modelling, Schema refinement ER to relational, logical DB design, physical DB design, security design

Question 29

ER Model

Answer 29

Entity, attribute, relationships

Question 30

Entity

Answer 30

real world object(rectangle)

Question 31

Domain

Answer 31

values permitted for an attribute

Question 32

Attribute

Answer 32

Property of an entity(oval)

Question 33

Relationship

Answer 33

association among 2 or more entities(diamond)

Question 34

Key

Answer 34

attribute or set of attributes which can uniquely identify an entity

Question 35

Prime attribute/key attribute

Answer 35

All attributes which are part of key

Question 36

Types of relationships

Answer 36

Unary, binary, ternary

Question 37

Unary

Answer 37

Employee manages employee

Question 38

Descriptive attribute

Answer 38

Attribute of relationship, educator teaches courses in dept since (here teaches, in are relationship and since is descriptive attribute)M

Question 39

Mapping cardinality

Answer 39

One to one, one to many, many to many

Question 40

One side represented by

Answer 40

Arrow

Question 41

Participation constaints

Answer 41

Total,partial

Question 42

Total

Answer 42

All entities take part in relationship, double line

Question 43

Partial

Answer 43

Not all entities take part in relationship, single line

Question 44

See questions in copy

Question 45

Weak entity

Answer 45

cannot be uniquely identified by its own attributes, double lined rectangle

Question 46

A weak entity set can only have a relation with a strong entity set true

Answer 46

True , identifying relationship(weak relationship),double diamond, and total participation from weak entity side.

Question 47

Dominant entity

Answer 47

Entity of strong entity set in a weak relationship

Question 48

Subordinate entity

Answer 48

Entity of weak entity set in a weak relationship

Question 49

We can identify subordinate entities using

Answer 49

Strong entities of a weak relationship

Question 50

Types of attributes

Answer 50

Single values, multi valued(double oval), composite, given, derived, prime, non prime,