Download Management Information Systems

CLARK UNIVERSITY
College of Professional and Continuing Education
(COPACE)
Management Information Systems
Lection 03
Database management system
Plan
•
•
•
•
•
•
•
Term “Database”
Architecture of database
Data models
Normal forms
Operations of relation algebra
Operations of SQL
DBMS
Term “Database”
• A huge amount of data is entered into
computer systems every day.
• Where does this data go and how is it used?
• How can it help you on a job?
Term “Database”
Widely database is a collection of facts about
real world’s objects if some field.
Field is a part of the real world which we learn
for managing: company, university, etc.
Non-structured data
Folder No. 16493, Smith John, 01/01/1976;
folder No. 16593, LeVering Barbara,
03/15/1975; folder No. 16693, McCow Robert,
04/14/1976.
Structured data
Folder No.
Surname
First name
Birth date
16493
Smith
John
01/01/1976
16593
LeVering
Barbara
03/15/1975
16693
McCow
Robert
04/14/1976
Structuring is the introduction of agreements on
the ways of presenting data.
Database definition
• Database (DB) is a named collection of
structured data related to a particular subject
area.
• Database management system (DBMS) - a set
of software and language tools necessary to
create databases, keeping them up to date
and organize the search in them the necessary
information.
Classification of databases
Data processing
Centralized
stored in a computer
system, which may be
the mainframe (access
via terminals) or file
server network.
Distributed
consists of several
parts, which are
stored in different
computer network
connection.
Classification of databases
Access to data
With local access
With network access
Classification of databases
Centralized database with network access can
have the following architecture:
 File-server
 Client-server
 Two-level model
 Three-level model
Architecture “File-level”
АрхитектArchitecture “File-level”ура
файл-сервер
1. Input and Display data
2. Data access and search Criteria
1. Keeping the database
file
3. Implementation of computing functions on the data
АрхитектArchitecture “File-level”ура
файл-сервер
Advantages:
1. The absence of very high performance of the server (most
importantly - the required amount of disk space)
2. The database is not running and will not being installed on a
server
Disadvantages:
1. High network traffic
2. Lack of special security arrangements file from the DB
Architecture “Client-server”
Architecture “Client-server”
1. Input and display data
2. Implementation of computing
functions on data sets
1. Keeping the database file
2. Access to the data and
search for certain criteria
Architecture “Client-server”
Advantages:
1. Lower network traffic than the file-server model
2. SQL-Server provides functions to ensure the integrity and security
of data
Disadvantages:
1. In certain cases, some data sets may take quite a substantial
amount of place
Two-level architecture
1. Input and Display data
1. Keeping the database file
2. Data access and search by
criteria
3. Implementation of computing
procedures on data sets
Two-level architecture
Advantages:
1. Significant reduction in network traffic compared to
client server
2. High reliability of data storage and processing
Disadvantages:
1. High demands on the computer server (disk space and speed)
Three-level architecture
Three-level architecture suggest the following application
components: a client application ("thin client" or a terminal)
connected to the application server, which in turn is connected to the
database server.
Data models
Stored data have a logical structure described by a
model of data (data model), supported by the DBMS.
Data model determines the organization of data,
constraints and the set of operations that are allowed
on the object.
Data models
 Hierarchical model
 Network model
 Relational model
Hierarchical model
The hierarchical model has been developed historically
in the first turn.
Based on this model it was created the first
professional DBMS IMS in the late 60's - early 70‘s
(IBM).
Hierarchical model
Links between different entities of data are described by
a structured graph or a tree
Hierarchical model
Advantage:
1. Sufficiently high run-time operations on data
Disadvantages:
1. Complexity of understanding for the average user
2. The presence of redundancy
Network model
Link between the data are described by an
arbitrary graph
Network model
Advantages:
1. Minimum redundancy
2. Compared to the hierarchical model the network model provides
a great deal in terms of the admissibility of the formation of new
links
3. Effective implementation in terms of memory consumption.
Disadvantages:
1. Complexity of understanding for the average user
2. Weakened control of the accuracy of links
Relational model
The relational model was proposed by Edgar Cod
in 1970.
Based on the concept of relation.
Graphically represented as a ratio of a table.
In a relational database assumes that the user
perceives the database as tables.
Relational model
Folder No.
Surname
First name
Birth date
Group
16493
Smith
John
01/01/1976
111
16593
LeVering
Barbara
03/15/1975
111
16693
McCow
Robert
04/14/1976
112
Relational model
Advantage:
1. Simplicity and clarity for a wide user, which is the reason of its
wide distribution.
Disadvantage:
1. Necessary redundancy because of the relationships between
tables.
Relational model
There are alternatives to the terms:
Alternative 1
Alternative 1
Alternative 1
Table
File
Relation
String
Record
Tuple
Column
Field
Domain
Primary key
Folder No.
Surname
First name
Birth date
Group
16493
Smith
John
01/01/1976
111
16593
LeVering
Barbara
03/15/1975
112
16693
McCow
Robert
04/14/1976
113
Primary key is a relation attribute (set of
attributes) that uniquely identifies each of its
records.
Student (FolderNo., Surname, First_name,
Birth_date, Group)
Foreign key
We can link tables by foreign keys.
Foreign key is an attribute (set of attributes) of relation,
which is the key of another relation.
Student(FolderNo., Surname, First_name, Birth_date,
Group)
Group(Number, Specialisation, Head_of_group)
Indexes
Index is a means to accelerate the search
operation records in the table, as well as other
operations that use search (retrieval, modification,
sorting, etc.)
Surname
Location
Location
Alekseev
1
1
Alekseev
Afanasiev
4
2
Yakovlev
Kuznecov
1000
3
Mikhailov
Mikhailov
3
4
Afanasiev
…
Yakovlev
…
Surname
…
2
1000
Kuznecov
Types of indexes
Indexes
Primary
The key field is always
indexed, so it doesn’t
require an additional
index.
Secondary
•The are used for enforcing
searching and executing
queries
•There might be several
secondary indexes
•They might include several
fields
•The same field can enter
different indexes
Data redundancy
Folder No.
Surname
First name
Birth date
Group
Specialization
15345
Ivanov
Ivan
04/15/1989
392
Informatics and
Management
15349
Medvedeva
Anna
02/13/1989
392
Informatics and
Management
15310
Petrov
Mikhail
11/12/1989
392
Informatics and
Management
15259
Sidorov
Nicolay
01/26/1987
591
Informatics and
English
15263
Sanin
Alexander
10/20/1987
591
Informatics and
English
The problem of update
Folder
No.
Surna
me
15345
Ivanov
15345
First
name
Birth
date
Gro
up
Specializa
tion
Term
Course
Score
Ivan
04/15/
1989
492
IM
2
English
Good
Ivanov
Ivan
04/15/
1989
492
IM
2
Theory of
algorithms
Excellent
15345
Ivanov
Ivan
04/15/
1989
392
?
IM
2
Chemistry
Good
15310
Petrov
Mikhail 11/12/
1989
392
IM
6
English
Satisfactory
15310
Petrov
Mikhail 11/12/
1989
392
IM
6
Theory of
algorithms
Satisfactory
15310
Petrov
Mikhail 11/12/
1989
392
IM
6
Chemistry
Good
15259
Sidorov Nicolay 01/26/
1987
591
IE
10
Architecture
of PC
Excellent
15259
Sidorov Nicolay 01/26/
1987
591
IE
10
Computer
modeling
Excellent
The problem of inserting new data
Folder
No.
Surname
First
name
15345
Ivanov
Ivan
15345
Ivanov
15345
Birth
date
Group
Specialization
Term
Course
Score
04/15 392
/1989
IM
2
English
Good
Ivan
04/15 392
/1989
IM
2
Theory of
algorithms
Excellent
Ivanov
Ivan
04/15 392
/1989
IM
2
Chemistry
Good
15310
Petrov
Mikhail
11/12 392
/1989
IM
6
English
Satisfactory
15310
Petrov
Mikhail
11/12 392
/1989
IM
6
Theory of
algorithms
Satisfactory
15310
Petrov
Mikhail
11/12 392
/1989
IM
6
Chemistry
Good
15259
Sidorov
Nicolay
01/26 591
/1987
IE
10
Architecture
of PC
Excellent
15259
Sidorov
Nicolay
01/26 591
/1987
IE
10
Computer
modeling
Excellent
15402
Stepanov Andrew 03/29 191
/1991
MSIT
1
-
-
Нормализация
The normalization of relations represent rules
of such formation of relations (tables) that allow
to eliminate duplication, inconsistency stored in
the database.
Нормализация
E. Codd developed three normal forms of
relations
and
the
mechanism,
which allows to convert any relation to the third
normal form.
Первая нормальная форма
(1НФ)
Table is in 1NF if each its cell has always the only
atomic value, and there can never be the set of
such values.
Folder
No.
Surname
15345
Ivanov
15310 Petrov
15259
Sidorov
First
name
Ivan
Первая
нормальнаяCourse
форма Score
Group Speciali- Term
zation
(1НФ)
Birth
date
04/15 392
/1989
Mikhail
Nicolay
11/12 392
/1989
01/26 591
/1987
IM
IM
IE
2
6
10
English
Good
Theory of
algorithms
Excellent
Chemistry
Good
English
Satisfactory
Theory of
algorithms
Satisfactory
Chemistry
Good
Architecture
of PC
Excellent
Computer
modeling
Excellent
The table is not in 1NF
First
name
Первая
нормальная
форма Score
Group SpecialiTerm
Course
zation
(1НФ)
Folder
No.
Surname
Birth
date
15345
Ivanov
Ivan
04/15 392
/1989
IM
2
English
Good
15345
Ivanov
Ivan
04/15 392
/1989
IM
2
Theory of
algorithms
Excellent
15345
Ivanov
Ivan
04/15 392
/1989
IM
2
Chemistry
Good
15310
Petrov
Mikhail
11/12 392
/1989
IM
6
English
Satisfactory
15310
Petrov
Mikhail
11/12 392
/1989
IM
6
Theory of
algorithms
Satisfactory
15310
Petrov
Mikhail
11/12 392
/1989
IM
6
Chemistry
Good
15259
Sidorov
Nicolay
01/26 591
/1987
IE
10
Architecture
of PC
Excellent
15259
Sidorov
Nicolay
01/26 591
/1987
IE
10
Computer
modeling
Excellent
Table is in 1NF
Диаграмма функциональных
зависимостей для примера БД «Студент»
Table is in 2NF if it does not contain any non-key attributes
which are functionally dependent on part of the key
Table is in 3NF if it does not contain any non-key
attributes, transitively dependent on the key part
45
Folder
No.
Surname
15345
Ivanov
First
name
Ivan
Birth Group проектирования
Group SpecialiРезультат
БД
date
zation
«Студент» 392 IM
04/15 392
/1989
15310
Petrov
Mikhail
11/12 392
/1989
15259
Sidorov
Nicolay
01/26 591
/1987
Folder No.
Term
591
Course
Score
15345
2
English
Good
15345
2
Theory of algorithms
Excellent
15345
2
Chemistry
Good
15310
6
English
Satisfactory
15310
6
Theory of algorithms
Satisfactory
15310
6
Chemistry
Good
15259
10
Architecture of PC
Excellent
15259
10
Computer modeling
Excellent
IE
SQL
A query language SQL (Structured Query
Language) provides an access to information
contained in relational databases for users,
software and computing systems
Relational algebra
SQL is based on relational algebra operations.
Relational Algebra is a set of operations on
relations.
Relational algebra was developed within the
relational model by Codd.
Using the relational algebra we can get other
relations
Relational algebra
Students of group 392
Union
No.
Surname
Name
Birth date
Group
15345
Ivanov
Ivan
04/15/1989
392
15349
Medvedeva
Anna
02/13/1989
392
15310
Petrov
Mikhail
11/12/1989
392
Students of group 591
No.
Surname
Name
Birth date
Group
15259
Sidorov
Nikolay
01/26/1987
591
15263
Sanin
Alexander
10/20/1987
591
Result
No.
Surname
Name
Birth date
Group
15345
Ivanov
Ivan
04/15/1989
392
15349
Medvedeva
Anna
02/13/1989
392
15310
Petrov
Mikhail
11/12/1989
392
15259
Sidorov
Nikolay
01/26/1987
591
15263
Sanin
Alexander
10/20/1987
591
Intersection
Relational algebra
Students of groups 392 and 591
No.
Surname
Name
Birth date
Group
15345
Ivanov
Ivan
04/15/1989
392
15349
Medvedeva
Anna
02/13/1989
392
15310
Petrov
Mikhail
11/12/1989
392
15259
Sidorov
Nikolay
01/26/1987
591
15263
Sanin
Alexander
10/20/1987
591
Students of group 392
No.
Surname
Name
Birth date
Group
15345
Ivanov
Ivan
04/15/1989
392
15349
Medvedeva
Anna
02/13/1989
392
15310
Petrov
Mikhail
11/12/1989
392
Result
No.
Surname
Name
Birth date
Group
15345
Ivanov
Ivan
04/15/1989
392
Substraction
Relational
algebra
Students of groups 392 and 591
No.
Surname
Name
Birth date
Group
15345
Ivanov
Ivan
04/15/1989
392
15349
Medvedeva
Anna
02/13/1989
392
15310
Petrov
Mikhail
11/12/1989
392
15259
Sidorov
Nikolay
01/26/1987
591
15263
Sanin
Alexander
10/20/1987
591
Students of group 392
No.
Surname
Name
Birth date
Group
15345
Ivanov
Ivan
04/15/1989
392
15349
Medvedeva
Anna
02/13/1989
392
15310
Petrov
Mikhail
11/12/1989
392
Result
No.
Surname
Name
Birth date
Group
15349
Medvedeva
Anna
02/13/1989
392
15310
Petrov
Mikhail
11/12/1989
392
15259
Sidorov
Nikolay
01/26/1987
591
15263
Sanin
Alexander
10/20/1987
591
Relational algebra
Selection
Students of groups 392 and 591
No.
Surname
Name
Birth date
Group
15345
Ivanov
Ivan
04/15/1989
392
15349
Medvedeva
Anna
02/13/1989
392
15310
Petrov
Mikhail
11/12/1989
392
15259
Sidorov
Nikolay
01/26/1987
591
15263
Sanin
Alexander
10/20/1987
591
Students of group 591
No.
Surname
Name
Birth date
Group
15259
Sidorov
Nikolay
01/26/1987
591
15263
Sanin
Alexander
10/20/1987
591
SQL
SELECT [DISTINC] elements
FROM table(s)
[WHERE condition]
[GROUP BY field(s) [HAVING condition]]
[ORDER BY field(s)]
SELECT – choose
DISTINC – eliminate the same strings in the output file
FROM – from which tables
WHERE – where if condition is true
GROUP BY – grouping strings by some field
HAVING – grouping under some condition
ОRDER BY – sorting
Select surnames of all students
Students
No.
Surname
Name
Birth date
Group
15345
Ivanov
Ivan
04/15/1989
392
15349
Medvedeva
Anna
02/13/1989
392
15310
Petrov
Mikhail
11/12/1989
392
15259
Sidorov
Nikolay
01/26/1987
591
15263
Sanin
Alexander
10/20/1987
591
Surname
Ivanov
Medvedeva
SELECT Surname FROM Students
Petrov
Sidorov
Sanin
Select all information about students of group 591,
sorting them by surname
Students
No.
Surname
Name
Birth date
Group
15345
Ivanov
Ivan
04/15/1989
392
15349
Medvedeva
Anna
02/13/1989
392
15310
Petrov
Mikhail
11/12/1989
392
15259
Sidorov
Nikolay
01/26/1987
591
15263
Sanin
Alexander
10/20/1987
591
SELECT * FROM Students WHERE Group=591
ORDER BY Surname
Result
No.
Surname
Name
Birth date
Group
15263
Sanin
Alexander
10/20/1987
591
15259
Sidorov
Nikolay
01/26/1987
591
Select birth date of Petrov
Students
No.
Surname
Name
Birth date
Group
15345
Ivanov
Ivan
04/15/1989
392
15349
Medvedeva
Anna
02/13/1989
392
15310
Petrov
Mikhail
11/12/1989
392
15259
Sidorov
Nikolay
01/26/1987
591
15263
Sanin
Alexander
10/20/1987
591
SELECT Birth Date FROM Students
WHERE Surname=“Petrov”
Birth date
11/12/1989
DBMS
Database management system (DBMS) is a set of
software and language tools necessary to create
databases, keeping them up to date and organize the
search the necessary information.
The term "database server" is generally used to refer to
the entire database, based on the "client-server",
including the server and client side.
Types of DBMS
Network DBMS (CronosPlus)
Hierarchical DBMS (IMS)
Rational (MS Access, Paradox, Interbase, FireBird,
MySQL, Oracle, Ingres)
Onject-oriented and object-rational (Oracle Database,
MicroSoft SQL Server)