Institute of Southern Punjab, Multan - WordPress.com · 2017-12-06 · Academic Honesty Your work...

Institute of Southern Punjab, Multan

Mr. Muhammad Nouman Farooq

BSC-H (Computer Science)

MS (Telecomm. and Networks)

Honors:

Magna Cumm Laude Honors Degree

Gold Medalist!

Blog Url: noumanfarooqatisp.wordpress.com

E-Mail: [email protected]

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Classification

Assignments & Quizzes 6% (6 Marks in Total)

Project & Presentation 9% (9 Marks)

Midterm Exams 25% (25 Marks)

Final Exam 50% (50 Marks)

Total 100 %

NOTE: 10% Marks will be Automatically given by Examination Deptt. on Attendance.

Grading Policy

Academic Honesty

Your work in this class must be your own

If students are found to have collaborated excessively or to

have cheated (e.g. by copying or sharing answers during an

examination), all involved will at a minimum receive grades of

“0” for the first violation

Further violations will result in failure in the course

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Attendance will be taken with in 15 minutes at the start of class

Students are allowed to enter into class with in 30 minutes at the starting

of class

Zero tolerance policy on attendance, discipline of class during lectures!

Assignments must be submitted on time, no late submissions

In case of copied assignment both parties will be given zero!

Projects, Presentation, Quizzes, Assignments, Class participation are very

important.

Don’t miss your Classes, Quizzes, Presentations, Assignments and

Projects!

Few Things to Remember!!

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Advance Database Systems

Lecture# 1

Overview of RDBMS

Recommended Books/Manuals

Modern Database Management - 8th Edition by Jeffery A. Hoffer, Prescott and McFadden

Fundamentals of Database Systems, By R. Elmasri and S. Navathe, 6th Edition, 2011

Database Systems-A Practical Approach to Design, Implementation and Management by

Thomas Connolly and Carolyn BEGG, 4th Edition

Database Systems – Design, Implementation, and Management-Carlos, Steven and Peter

(9th Edition)

A Guide To MySQL 8th Edition by Philip J. Pratt & Mary Z. Last

A guide to Advance MySQL latest Edition by Muhammad Nouman Farooq

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Lecture 1: Overview of RDBMS

Database Definitions and Advantages of RDBMS

Hierarchical Structure of DBMS

Introduction to File Processing Systems

Advantages of Database Approach

System Development Life Cycle (SDLC)

Database Development Process (DDP)

The Three-Level ANSI-SPARC Architecture

Relational Data Structure

Relational Keys

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8

Jonathan Abrams Friendster fails due to

not optimized and efficient Database

System

Mark Zuckerberg Facebook did not fail

due to optimized and efficient Database

System

Database Definitions and Advantages

of RDBMS

10

Database Definitions

An organized collection of information in computerized format.

A collection of information organized and presented to serve a

specific purpose

11

Continued…

The term database is often incorrectly referred to as a synonym for a

“database management system (DBMS)”.

12

Continued…

Each of the above given definition are correct, and describe

database from slightly variant perspectives.

From exam point of view, anyone will do. However, within

this course, we will be referring first of the above

definitions more frequently, and concepts discussed in the

definition like, logically related data, shared collection

should be clear.

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Data and Information Data is the collection of raw facts collected from any specific

environment for a specific purpose.

Data in itself does not show anything about its environment, so to

get desired types of results from the data we transform it into

information by applying certain processing on it.

Once we have processed data using different methods; than data is

converted into meaningful form and that form of the Data is called

information.

15

Continued…

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Continued…

If we consider the data in the previous figure without the titles or the

labels associated with the data (EmpName, age, salary) then; it is not

much useful.

However, after attaching these labels it brings some meanings to us,

this meaningfulness is further increased when we associate some other

labels, like the company name and the department name etc.

So this is a very simple example of processing that we can do on the

data to make it information.

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18

Continued…

Database Systems

The term database system is a combination of database and

the Database Management System (DBMS).

So, database is collection of meaningful data/information,

DBMS is a tool to manage this data, and both jointly are called

database system.

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Why Use Models?

Models can be useful when we want to examine or manage part of

the real world.

The costs of using a model are often considerably lower than the

costs of using or experimenting with the real world itself.

Examples:

Network Model Simulation for an Organization in Packet Tracer

World Map

ERD for Relational Database Systems

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21

Flat File Vs Relational Database

System

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Flat File Vs Relational Database

System

A flat file database is a database designed around a single table.

The flat file design puts all database information in one table, or

list, with fields to represent all parameters.

A flat file may contain many fields, often, with duplicate data that

are prone to data corruption.

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Continued…

If you decide to merge data between two flat files, you need to

copy and paste relevant information from one file to the other.

There is no automation between flat files.

If you have two or more flat files that contain client addresses, for

example, and a client moved, you would have to manually modify

the address parameters in each file that contains that client’s

information.

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Relational Database System

A relational database, on the other hand, incorporates multiple

tables with methods for the tables to work together.

The relationships between table data can be ordered, merged

and displayed in database forms.

These tables are to be normalized up to 3rd Normal Form (3-NF).

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File Processing System

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46

Continued…

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48

Database System Environment

It will be helpful to reiterate our database definition here, that

is, “Database is a shared collection of logically related data,

designed to meet the information needs of multiple users in an

organization”

A typical database system environment is shown in the figure on

next slide.

49

Continued…

50

Continued…

The figure shows different subsystem or applications in an

educational institution, like library system, examination system,

and registration system. There are separate, different application

programs for every application or subsystem.

However, the data for all applications is stored at the same place

in the database and all application programs, relevant data and

users are being managed by the DBMS.

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The data for different applications or subsystems is placed at the

same place. This introduces the major benefit of data sharing. That

is, data that is common among different applications need not to be

stored repeatedly, as was the case in the file processing

environment.

For example, all three systems of an educational institution shown

in figure need to store the data about students.

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1-Data Sharing

Now the data like registration number, name, address, father

name that is common among different applications is being

stored repeatedly in the file processing system environment,

where as it is being stored just once in database system

environment and is being shared by all applications.

53

Continued…

Data and programs are independent of each other, so change is

one has no or minimum effect on other

Means that we do not need to duplicate data

unnecessarily; we do duplicate data in the databases,

however, this duplication is deliberate and controlled.

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2-Data Independence

3-Controlled Redundancy

Very important feature; means the validity of the data being entered in

the database. Since the data is being placed at a central place and

being managed by the DBMS, so it provides a very helpful to check or

ensure that the data being entered into the database is actually valid.

We can also define it as Level of Correctness of Data.

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4-Data Integrity:

5-Better Data Security

All application programs access data through DBMS, So

DBMS can very efficiently check that which user is

performing which action and accessing which part of

data.

So, A DBMS is the most effectively control and maintain

security of Data stored in a database.

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6-Faster Development of new Applications

The database environment allows us faster application

development because of its many reasons.

As we know that database is designed focusing the

conclude result to meet the expectations of the client.

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7-Better Concurrency Control

Concurrency means the access of database form as number of pointssimultaneously.

Concurrency Control means to access the database in such a waythat all the data accesses are completed correctly andtransparently.

One example of controlled concurrency is the use of ATM Machinefor withdrawal of money (cash).

All ATM machines of a bank are interconnected to a centraldatabase system worldwide, so that a user can access its accountfrom anywhere in the world and can get cash from any ATMterminal.

58

Continued…

As there are thousands of ATM terminal across the world for a

specific bank so as a result thousands of user process and access

the bank’s database.

All this process is managed concurrently using the database

systems and is done in such an efficient manner that no two user

face any delay in the processing of their requests.

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8-Better Backup and Recovery Facility

Some time happens that a database which was in use and very

important transactions were made after the last backup was made,

all of a sudden due to any disastrous situation the database

crashes (improper shutdown, invalid disk access, etc.)

Now, In such a situation the database management system should

be able to recover the database to a consistent state so that the

transactions made after the last backup are not lost.

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Database Development Process

Database Application development Process includes theFollowing Stages or steps:

1. Preliminary Study

2. Requirement Analysis

3. Database Design

4. Physical Design

5. Implementation

6. Maintenance

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Continued…

66

Preliminary Study

Design of database is carried out in a number of steps; these steps

play important role in the design process and need to be given

proper attention.

First Phase of the database development process is the Preliminary

Study, which is based on the proper study of the system.

It means that all the parts of the systems, or the section of the

subject organization for which we intend to develop the system

must be studied.

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Continued…

We should find the relation or interaction of different section of the

organization with each other and should understand the way

information flows between different sections of the organization.

Moreover it should also be made clear that what processing is

performed at each stage of the system.

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Requirement Analysis Once we have investigated the organization for its different sections

and the way data flows between those sections; Detailed study of the

system is started to find out the requirements of each section.

In second phase, The detailed study of the system and its

functionality decisions made at this stage decide the overall activity

of the organization.

Requirements of one section of the organization are fulfilled in such a

way that all the sections in the organization are supporting each

other.

For example we can say that the results produced by the processing

taking place at one section are used as input for another section.69

Database Design

Third phase in the database development process is the database

design.

This is a technical phase of the process and need handsome skill as

a Database Administrator. This is the phase where the conceptual

design of the database is created. It also known as Conceptual Data

Modeling.

Entities are identified and given attributes, relationships are built

and different types of relationship are performed by assigning

cardinalities.70

Physical Design

In fourth phase, The choice of the DBMS is made on the basis of

requirements and the environment in which the system will operate.

Implementing a database on a specific DBMS is very important

because it involves the major financial investment of the

organization, and can not be reverted in case a selected DBMS in not

capable of providing the desired efficiency.

Also, Assigning meaningful Data Types, Constraints/Limitations and

De-Normalization of Data where required by the real time

scenario/system are to be finalized and processed in this phase.

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Implementation

This phase is specific to writing the application programs needed to

carry out different activities according to user requirements.

We must write application programs in this phase by using MySQL

(mai-structured query language) by using DBMS engine known as

XAMPP (Cross platform apache MySequel PHP Perl).

We can done coding with out any logical error; If we have

implemented all previous phases of database development process

correctly.

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Maintenance

Maintenance means to fine tune the system and check that the

designed applications systems are fulfilling the purpose for which

they are meant.

Also, this phase may involve designing any new application for the

enhancement of the system.

Or an already working application may need to be updated or

modified to remove any errors or to add some functionality in the

system.

73

Continued…

All these stages are necessary and must be given the necessary

attention at each level to get properly working and good system design

and a better working environment.

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The Three-Level ANSI-SPARC

Architecture

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Three Level ANSI-SPARC Architecture

The levels form a three-level architecture comprising an External,

Conceptual, and an Internal level.

The way users observe the data is called the External Level (Front

End). The way the DBMS and the Operating System perceive/stores

the data (Back End) is the Internal Level.

The Conceptual Level provides both the mapping and the desired

independence between the external and internal levels.

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Continued…

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Continued…

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Continued…

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The overall Description/Skeleton structure of the database is called the

database schema.

At the highest level, we have multiple external schemas (also called

subschemas) that correspond to different views of the data.

At the conceptual level, we have the conceptual schema, which describes

all the entities, attributes, and relationships together with integrity

constraints.

At the lowest level, we have the internal schema, which is a complete

description of the internal model, containing the definitions of stored

records, the methods of representation, the data fields, and the indexes

and storage structures used. There is only one conceptual schema and one

internal schema per database.

Continued…

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Continued…

The objective of the three-level architecture is to separate each

user’s view of the database from the way the database is physically

represented. There are several reasons why this separation is

desirable:-

1. Each user should be able to access the same data, but have a

different customized view of the data.

2. Users should not have to deal directly with physical database

storage details.

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Continued…

4. The internal structure of the database should be unaffected by

changes to the physical aspects of storage, such as the changeover

to a new storage device.

5. The Database Administrator (DBA) should be able to change the

conceptual and database storage structures without affecting the

users’ views.

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Continued…

A major objective for the three-level architecture is to provide data

independence, which means that upper levels are unaffected by

changes to lower levels.

There are two kinds of data independence: -

1. Logical Data Independence.

2. Physical Data Independence.

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Continued…

84

Continued…

1. Logical Data Independence: -

Changes to the conceptual schema, such as the

addition or removal of new entities, attributes, or relationships,

should be possible without having to change existing external schemas

or having to rewrite application programs. Clearly, the users for whom

the changes have been made need to be aware of them, but what is

important is that other users should not be.

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Continued…

2. Physical Data Independence: -

Changes to the internal schema, such as using

different file storage structures, using different storage devices should

be possible without having to change the conceptual or external

schemas.

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Relational Keys

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Relational Keys

Keys are used to create relationship among different database tables.

An entity type may have many instances, from a few to severalthousands and even more.

Now out of many instances, when and if we want to pick aparticular/single instance, and many times we do need it, then key isthe solution.

For example, think of whole population of Pakistan, the data of allPakistanis lying at one place, say with NADRA people. Now if atsometime we need to identify a particular person out of all this data,how can we do that?

92

Continued…

While defining an entity; we also generally define the key of that

entity. How do we select the key, from the study of the real-world

system; key attribute(s) already exist there, sometimes they don’t

automatically enabled; then the designer has to define one.

A key can be simple, that is, consisting of single attribute, or it

could be composite which consists of two or more attributes.

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Super Key

Candidate Key

A super key for which no subset is a super key is called a candidate

key, or the minimal super key is the candidate key.

It means that there are two conditions for the candidate key, One; It

identifies the entity instances uniquely, as is required in case of

super key, Second; It should be minimum, that is, no proper subset

of candidate key is a key.

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Continued…

So, If we have a simple super key, that is, that consists of single/simple

attribute, it is definitely a candidate key, 100%.

However, if we have a composite super key and if we take any attribute out

of it and remaining part is not a super key anymore then that composite

super key is also a candidate key since it is minimal super key.

For example, one of the super keys that we identified from the entity

STUDENT is “regNo, name”, this super key is not a candidate key, since if

we remove the regNo attribute from this combination, name attribute

alone is not able to identify the entity instances uniquely.

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Primary Key

A candidate key chosen by the database designer to act as key is the

primary key.

An entity type may have more than one candidate keys, in that case

the database designer has to designate one of them as primary key,

since there is always only a single primary key in an entity type.

If there is just one candidate key then obviously the same will be

declared as primary key. The primary key can also be defined as the

successful candidate key.

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Continued…

The relation that holds between super and candidate keys also

holds between candidate and primary keys, that is, every primary

key (PK) is a candidate key and every candidate key is a super key.

A certain value that may be associated with any attribute is NULL,

that means “not given” or “not defined”.

A major characteristic of the Priamary Key is that it cannot have

the NULL value.

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Unique Key

A candidate key which can return a Record uniquely but may store a

NULL value is called as Unique Key.

stdContactNumber attribute in STUDENT table is known as Unique

key.

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Alternate Key

Candidate keys which are not chosen as the primary key are known

as alternate keys.

For example, we have two candidate keys of EMPLOYEE in figure 2,

regNo and nIdNumber, if we select regNo as PK then the nIdNumber

will be alternate key.

100

Foreign Key

Sometimes the information stored in a relation is linked to the

information stored in another relation.

If one of the relations is modified, the other must be checked, and

perhaps modified, to keep the data consistent.

101

Continued…

Suppose that in addition to Students, we have a second relation:

Enrolled (cId: string, sId: string, cGrade: Text)

The sId field of Enrolled is called a foreign key and refers to

Students.

The foreign key in the referencing relation (Enrolled, in our example)

must match the primary key of the referenced relation (Students),

i.e., it must have the same number of columns and compatible data

types, although the column names can be different.

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Continued…

103

Continued…

As the figure shows, there may well be some students who are not

referenced from Enrolled

(e.g., the student with sId=50000)

However, every sId value that appears in the instance of the Enrolled

table appears in the primary key column of a row in the Students

table.

104

Continued…

If we try to insert the tuple (55555, Art104, A) into E1, the rule is

violated because there is no tuple in S1 with the id 55555; the

database system should reject such an insertion.

Similarly, if we delete the tuple (53666, Jones, jones@cs, 18, 3.4)

from S1, we violate the foreign key constraint because the tuple

(53666, History105, B) in E1 contains sid value 53666, the sid of the

deleted Students tuple.

The DBMS should disallow the deletion or, perhaps, also delete the

Enrolled tuple that refers to the deleted Students tuple.105

Continued…

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Secondary Key

Many times we need to access certain instances of an entity type

using the values of one or more attributes other than the PK.

The difference in accessing instances using the value of a key or

non-key attribute is that the search on the value of PK will always

return a single instance (if it exists), where as uniqueness is not

guaranteed in case of non-key attribute.

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Continued…

Such attributes on which we need to access the instances of an

entity type that may not necessarily return unique instance is called

the secondary key.

For example, we want to see how many of our students belong to

Multan, in that case we will access those instances of the STUDENT

entity type that contain “Multan” in their address.

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Continued…

In this case address will be called secondary key, since we are

accessing instances on the basis of its value, and there is no

compulsion that we will get a single instance.

Keep one thing in mind here, that a particular access on the value of

a secondary key MAY return a single instance, but that will be

considered as chance.

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Continued…

There is not the compulsion or it is not necessary for secondary key

to return unique instance

But; In case of super, candidate, primary and alternate keys it is

compulsion that they will always return unique instance against a

particular value.

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Surrogate Key:

A Surrogate Key is any column or set of

columns that can be declared as the primary key instead of more

than two composite Primary keys that jointly makes a Cumbersome

key (CUMBERSOME meaning: Large Set).

Example of Cumbersome key and Surrogate key

is shown in next slide.

Continued…

112

b) Mapping the ternary relationship PATIENT TREATMENT

Remember

that the

primary key

MUST be

unique

This is why

treatment date

and time are

included in the

composite

primary key

But this makes a

very

Cumbersome

Key…

It would be better to create a

Surrogate Key like treatmentId

in PATIENT_TREATMENT table

Quick Review of Relational Keys Concept’s

113

Every Candidate Key must be a Super Key. But, Every SuperKey may not be a Candidate Key.

Every Primary Key must be a Candidate Key. But, EveryCandidate key may not be a Primary Key.

Every Alternate Key must be a Candidate Key. But, EveryCandidate key may not be a Alternate Key.

Every Foreign Key must be a Primary Key.

Every Secondary Key must not be a Candidate Key & PrimaryKey & Alternate Key.

Cumbersome Key (Group of Composite Primary Keys) can bereplaced by Surrogate Key

Class Activity

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Class Activity (Solution)

115

Recommended Readings

Chapter 1 from: -

Database Systems-A Practical Approach to Design,

Implementation and Management by Thomas Connolly and

Carolyn BEGG, 4th Edition (Page No. 54-67)

Modern Database Management - 8th Edition by Jeffery A.

Hoffer, Prescott and McFadden (Page No. 34-62)

116

Continued…

Chapter 2 from: -

Modern Database Management – 8th Edition by Jeffery A. Hoffer,

Prescott and McFadden (Page No. 84-103)

Database Systems-A Practical Approach to Design, Implementation

and Management by Thomas Connolly and Carolyn BEGG, 4th Edition

(Page No. 69-114)

Fundamentals of Database Systems – 6th Edition by Elmasri and

Navathe (Page No. 58-83)

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Chapter 5 from:

Modern Database Management – 8th Edition by Jeffery A. Hoffer,

Prescott and McFadden (Page No. 220-230)

Chapter 3 from:

Database Systems-A Practical Approach to Design,

Implementation and Management by Thomas Connolly and

Carolyn BEGG, 4th Edition (Page No. 120-138)

118

Continued…

Summary of Lecture

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Lecture 1➦

Database Definitions and Advantages of RDBMS




Summary of Lecture (Continued..)

120

Lecture 1➦



The Three-Level ANSI-SPARC Architecture


Relational Keys

END OF LECTURE 1

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