Overview of Relational DBMS

7/28/2019 Overview of Relational DBMS

1/34

Overview Of Relational DBMSPresented by

Satrio Agung Wicaksono


2/34

Relational Database Concepts A database is a repository of data, designed to support

efficient data storage, retrieval and maintenance

Relational databaseis a database modeled by relations

RelationR defined over n sets D1, D2, Dnwhere Di

represents some domain.

n-tuple(tuple) is a set < d1, d2, , dn> where d1D1,d2D2,


3/34

Sample Database Scheme

The relation schemas for this database can be defined as

follows:

EMP(ENO, ENAME, TITLE, SAL, PNO, RESP, DUR)

PROJ(PNO,PNAME, BUDGET)


4/34

Key Super Key:

uses keys to define identifiers for a relations tuples

used to enforce rules and/or constraints on database data.

Candidate Key

is a unique identifier for the tuples of a relation

most relations have multiple candidate keys

Primary Key

candidate key that is chosen to represent the relation in the database and to provide a wayto uniquely identify each tuple of the relation

Alternate Key

the remaining candidate keys


5/34

The problem of redundancy Data redundancy implies finding the same data in

more than one location within deatabase tables

The following problems Repetition anomaly

Insertion Anomalies

Deletion Anomalies

Update Anomalies

Contd.


6/34

Repetition anomaly

Repetition anomaly :

Certain information may be repeated unnecessarily

This is obviously a waste of storage and is contrary to the spirit of

databases

NIM NAMA PRODI K_MK THN_MK THN_AKADEMIK SEMESTER NAMA_MK SKS NILAI

10509xxx Wira Ilkom SIF15012 2012 2012 Ganjil BDT 3 A

10509xxx Wira Ilkom SIF15011 2012 2012 Ganjil ABD 3 A


7/34

Insertion Anomalies

insertion anomaly : happens when the insertion of a

data record is not possible unless we also add someadditional unrelated data to the record



10509xxx Wira Ilkom SIF15011 2012 2012 Ganjil ABD 3 A


8/34

Deletion Anomalies

deletion anomaly happens when deletion of a data

record results in losing some unrelatedinformation that was stored as part of the record

that was deleted from a table

NIM NAMA PRODI K_MK THN_MK THN_AKADEMIK SEMESTER NAMA_M

K

SKS NILAI


10506xxx Wiri TIF SIF15012 2012 2012 Ganjil BDT 3 A


9/34


10/34

Decompositions

Decomposition in relational database design implies breaking down a relational

schema into smaller and simpler relations that avoid redundancy.

The idea is to be able to query the smaller relations for any information that we

were previously able to retrieve from the original relational schema



10506xxx Wiri TIF SIF15012 2012 2012 Ganjil BDT 3 A

NIM NAMA PRODI

10509xxx Wira Ilkom

10506xxx Wiri TIF

NIM K_MK THN_MK THN_AKADEMIK SEMESTER NAMA_MK SKS NILAI

10509xxx SIF15012 2012 2012 Ganjil BDT 3 A

10506xxx SIF15012 2012 2012 Ganjil BDT 3 A


11/34

Functional Dependencies Functional Dependency (FD) i:

a type of integrity constraint that extends the idea of a super key.

It defines a dependency between subsets of attributes of a given relation

Functional Dependency can be understood as A determines B, B is

dependent on A or A implies B and denoted as A B.


12/34

Functional Dependencies Example

Set Of Functional Dependecies ?

NIM NAMA PRODI K_MK THN_KURIKULUM THN_AKADEMIK SEMESTER NAMA_MK NILAI

10509xxx Wira Ilkom SIF15012 2012 2012 Ganjil BDT A

10509xxx Wira Ilkom SIF15011 2012 2012 Ganjil ABD A


13/34

Normal Forms Normalization is a procedure in relational database design that

aims at converting relational schemas into a more desirableform

The goal is to remove redundancy in relations and the problemsthat follow from it, namely insertion, deletion and updateanomalies.

Type of Normal Form:

First Normal Form (1NF)

Second Normal Form (2NF)

Third Normal Form (3NF)

Boyce-Codd Normal Form (BCNF


14/34

First Normal Form (1NF) A relation is considered to be infirst normal form if all of its attributes have

domains that are indivisible or atomic

A table is in 1NF if and only if it satisfies the following five conditions :

There is no top-to-bottom ordering to the rows.

There is no left-to-right ordering to the columns.

There are no duplicate rows

Every row-and-column intersection contains exactly one value from the applicable domain

(and nothing else).

All columns are regular [i.e. rows have no hidden components such as row IDs, object IDs,

or hidden timestamps].

Contd.


15/34

First Normal Form (1NF)NIM NAM

A

NO_HP FAK PROD

I

K_MK THN_KURIK

ULUM

THN_AKADE

MIK

SEMESTE

R

NAMA_

MK

SKS NILA

I

10509xx

x

Wira 0821xxx

08775xx

PTIIK Ilkom SIF150

12

2012 2012 Ganjil BDT 3 A

10506xx

x

Wiri 08555xx

0888xxx

PTIIK TIF SIF150

12


NIM NAM

A

NO_HP FAK PRO

DI

K_MK THN_KURI

KULUM

THN_AKADE

MIK

SEMESTE

R

NAMA_

MK

SKS NIL

AI

10509xx

x

Wira 0821xxx PTII

K

Ilkom SIF1501

2


10509xx

x

Wira 08775xx PTII

K

Ilkom SIF1501

2


10506xx

x

Wiri 08555xx PTII

K

TIF SIF1501

2


10506xxx

Wiri 0888xxx PTIIK

TIF SIF15012


1NF transformation


16/34

First Normal Form (1NF)NIM NAM

A

NO_HP FAK PRO

DI

K_MK THN_

MK

THN_AKADE

MIK

SEMEST

ER

NAMA_

MK

SKS NILAI

10509xx

x

Wira 0821xxx

08775xx

PTIIK Ilkom SIF150

12


10506xx

x

Wiri 08555xx

0888xxx

PTIIK TIF SIF150

12


NIM NAMA FAK PRODI

10509xxx Wira PTIIK Ilkom

10506xxx Wiri PTIIK TIF NIM NO_HP

10509xxx 0821xxx

10509xxx 08775xx

10506xxx 08555xx

10506xxx 0888xxx

NIM K_MK THN_M

K

THN_AKADEM

IK

SEMESTE

R

NAMA_

MK

SKS NILA

I

10509xx

x

SIF150

12


10506xx

x

SIF150

12



17/34

Second Normal Form (2NF)

A relation is in second formal form when it is in 1NF and there is no suchnon-key attribute that depends on part of the candidate key, but on the

entire candidate key

NIM NAMA FAK PRODI

10509xxx Wira PTIIK Ilkom

10506xxx Wiri PTIIK TIF

NIM NO_HP

10509xxx 0821xxx

10509xxx 08775xx

10506xxx 08555xx

10506xxx 0888xxx

NIM K_MK THN_MK THN_AKADEMIK SEMESTER NILAI

10509xxx SIF15012 2012 2012 Ganjil A

10506xxx SIF15012 2012 2012 Ganjil A

K_MK THN_MK NAMA_MK SKS

SIF15

012

2012 BDT 3

SIF15

012

2012 BDT 3


18/34

Third Normal Form (3NF) A relation is in third normal form if it is in 2NF and there is no such non-key

attribute that depends transitively on the candidate key.

That is every attribute depends directly on the primary key and not through

a transitive relation where an attribute Z may depend on a non-key attributeY and Y in turn depends on the primary key X

Transitivity means that when XY and Y Z, then XZ.

Contd


19/34

Third Normal Form (3NF)

NIM NAMA PRODI

10509xxx Wira Ilkom

10506xxx Wiri TIF

NIM NO_HP

10509xxx 0821xxx

10509xxx 08775xx

10506xxx 08555xx

10506xxx 0888xxx

NIM K_MK THN_MK THN_AKADEMIK SEMESTER NILAI

10509xxx SIF15012 2012 2012 Ganjil A

10506xxx SIF15012 2012 2012 Ganjil A

K_MK THN_MK NAMA_MK SKS

SIF15

012

2012 BDT 3

SIF15

012

2012 BDT 3

FAK PRODI

PTIIK Ilkom

PTIIK TIF


20/34

Boyce-Codd Normal Form (BCNF) Boyce-Codd Normal Form is a stricter version of 3NF that applies to

relations where there may be overlapping candidate keys.

A relation is said to be in Boyce-Codd normal form if it is in 3NF and everynon-trivial FD given for this relation has a candidate key as its determinant.

That is, for every X Y, X is a candidate key.


21/34

Boyce-Codd Normal Form (BCNF)K_MK THN_MK THN_AKADEMIK SEMESTER KELAS PRODI HARI_KE

SIF15012 2012 2012 Ganjil A ILKOM 1

SIF15012 2012 2012 Ganjil A TIF 2

PTI15007 2012 2012 Ganjil A TIF 2

PTI15007 2012 2012 Ganjil A TIF 5


22/34

Relational Algebra Relational algebra is a set of operators to

manipulate relations

Defined 8 such operators, two groups of 4 each:

The traditional set operations: union, intersection,

difference and Cartesian product

The special relational operations: select, project, join anddivide


23/34

Union The union of two union-compatible relations R1 and R2, R1 UNION R2, is the set of all

tuples t belonging to either R1 or R2 or both

The formal notation for a union operation is U


24/34

Intersection The intersection of two union-compatible relations R1 and R2, R1

INTERSECT R2, is the set of all tuples t belonging to both R1 and R2.

The formal notation for an intersect operation is .


25/34

Difference The difference between two union-compatible relations R1 and R2, R1

MINUS R2, is the set of all tuples t belonging to R1 and not to R2.

The formal notation for a difference operation is -


26/34

Cartesian product The Cartesian productbetween two relations R1 and R2, R1 TIMES R2, is the set of all tuples t

such that t is the concatenation of a tuple r belonging to R1 and a tuple s belonging to R2. The

concatenation of a tuple r = (r1, r2, , rm) and a tuple s = (sm+1, sm+2, , sm+n) is the tuple t

= (r1, r2, , rm, sm+1, sm+2, , sm+n).

R1 and R2 dont have to be union-compatible.

The formal notation for a Cartesian product operation is


27/34

Selection The selectoperation selects a subset of tuples from a relation.

It is a unary operator, that is, it applies on a single relation.

The tuples subset must satisfy a selection condition or predicate.

The formal notation for a select operation is:

()

where is

/ [AND/OR/NOT

/]

The comparison operator can be , =, =, and it depends on attribute domain or

data type constant value


28/34

Selection


29/34

Projection Theprojectoperation builds another relation by selecting a subset of

attributes of an existing relation.

Duplicate tuples from the resulting relation are eliminated. It is also a unary

operator.

The formal notation for a project operation is:

()

where is the subset attributes of an existing relation


30/34

Projection


31/34

JOIN Thejoin operation concatenates two relations based on a joining condition

or predicate.

The relations must have at least one common attribute with the same

underlying domain, and on such attributes a joining condition can bespecified.

The formal notation for a join operation is:

R S

where is

<

The comparison operator can be , =, =, and it depends on attributes domain.


32/34

JOIN


33/34

Division The division operator divides a relation R1 of degree (n+m) by a relation R2

of degree m and produces a relation of degree n.

The (n+i)th attribute ofR1 and the ith attribute from R2 should be defined

on the same domain.

The result of a division operation between R1 and R2 is another relation,

which contains all the tuples that concatenated with all R2 tuples are

belonging to R1 relation.

The formal notation for a division operation is .


34/34

Division

Documents

Overview of Relational DBMS