DATABASE MANAGEMENT SYSTEM
Sayed AhmedComputer Engineering, BUET, BangladeshMSc, Computer Science, U of Manitoba, Canada
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Learning Objectives Concept of Database and Database
Management System Activities of a Database Management
System What is a Relational Database
Management System Features of Relational Database
Management System
Learning Objectives Create database Concept and explain the importance of
Data Security Data Encryption
ImportanceMethods
Querying Database: Query Language: SQL
Uses of Databases
What is a Database? Database means
Data storageA good/organized/efficient way of storing dataYou can store all the information of a public
library/bank into a database How are information stored in computers?
In files; you know it when you learn to use computers
Files are stored in computer hard drives, USB sticks, memory cards
What is a Database Is there anything different of storing data
by a databaseNot much, databases also store data in filesHowever, a database stores data in files in a
very organized way so that it becomes easier to○ Insert new data into the file/files○ Easier to search, sort, and retrieve data from
those files
What is a Database Let’s see, you can store all information
of a bank in a single computer fileAll bank account informationAll employee informationAll account holder informationAll branch and department informationYou can keep them in a single file; but can
be very difficult to find something useful fast; also inserting data and managing the file can be difficult
What is a Database Now you can store all data in multiple files; just divide
the original file into multiple files;○ Still if you do not organize the files or the data in them, it can
be very difficult to work with them○ In a database, information are kept eventually in computer files
However, a database will use a good strategy on how to store those data into files
Databases will store the data in many files Will store in such a way so that it becomes easier to work with the files
and the data In real life, we have systems and software that knows about the
strategy and helps to deal with those files and data for efficient storing, searching, retrieving, doing operations on the data and store the result in the same database- We call such systems and software to be the Database Management
System
What is a database One strategy
Keep one type of data into one file○ Such as in one file, store all bank account holders personal
information○ In another file, keep the details of all the bank accounts ○ In another file, keep the association between these accounts
and account holders○ If the number of records in a file is two many, divide the files
into multiple files but keeping the same type of information; find a way to keep track which files are related
○ Create some other files to keep track of which files store what○ Create some other files that can store the
location/address/position of a particular data in other files [index file]
What is a Database Management System If we have software that implements the
strategy described above, can be called a DBMS
When we feed data into it, if it can store the data using that strategy and provides ways to manipulate the data in an efficient wayThen we can call this software to be a DBMSDBMSes usually display data in tabular format
(row/column - format)
Database and Database Management Systems From Wikipedia, the free encyclopedia A database
is an organized collection of data. The data are typically organized to model relevant aspects of reality in a way that supports processes requiring this information. For example, modeling the availability of rooms in hotels in a way that supports finding a hotel with vacancies
Database management systems (DBMSs) are specially designed applications that interact with the user, other
applications, and the database itself to capture and analyze data. A general-purpose database management system (DBMS) is a software system designed to allow the definition, creation, querying, update, and administration of databases. Well-known DBMSs include MySQL, PostgreSQL, SQLite, Microsoft SQL Server, Microsoft Access, Oracle, SAP, dBASE, FoxPro, IBM DB2, LibreOffice Base and FileMaker Pro. A database is not generally portable across different DBMS, but different DBMSs can inter-operate by using standards such as SQL and ODBC or JDBC to allow a single application to work with more than one database.
Activities provided by a DBMS DBMS can create a database
i.e. Create the initial structure of the databaseAllocate space and saves the database in the hard drive
Control who can use a database Take data from user and record and store it
somehow Organize data
In meta files or in actual data files Provide means to search and display the data Provide security of the data Maintain the integrity of the data
Advantages of a DBMS Improved availability
To different users, efficient retrieval of data Minimized redundancy
Data are organized in a way so that the same data are not stored in multiple places/files
AccuracyCan keep data consistent as 1. redundancy
reduced and 2. data is available through one interface (DBMS interface)
Advantages of a DBMS Program and file consistency
Standardizes the storing of data; so others can use it easily
User-friendlyEasier to deal with [usually provide
friendly interface] Improved security
Control who can access the database
Relational Database Model Just a strategy to store and manipulate data
The strategy we talked about indirectly refers to relational model
Based on relational modelWhat is a relational model?
○ it is a method of structuring data using relations, which are grid-like/matrix-like mathematical structures consisting of columns and rowsTable is the physical manifestation of a relation in a
databaseSo data are stored in tables (row/column wise) in
Relational Database Models
Relational Database Model It is composed of one or more tables [to
represent data] Tables also represent the
relations/associations of different related data
So here, we have tables of data Tables has columns called fields Tables are linked/related to other related
tables by common columns/fieldsPrimary key/foreign key concept
Relational Model for A Library Books: Book Information
Id, title, published, price Authors: Author Information
Id, name, SIN, address Members: member information
Id, name, SIN, address, phone, email Book-Borrowers:
Relation between books and membersBookid, memberid, date
Relational Model
Features of Relational DBMS Provide easy ways to create tables Provide easy ways to create relations
among tables Provide ways to insert, update, search
data in a table or from multiple tables Provide ways to validate data at insertion Provides language such as SQL for data
insertion, update, and search Support multiple views of data
Features of Relational DBMS It is easy to create application software
having relational database in the backend
Usage of Relational DBMS Airlines reservation system Banking management system Online banking system Hospital operation management
systems Library management system
Creating Databases What does it involves?
In DBMS, usually there is an option to create databaseIt may ask for initial size of the databaseHow to increment the size of the databaseCharacter encoding of the databaseModel to use for creating the database (relational,
object oriented)Security/access control for the databasePath to store the database filesThen it will create the basic structure of the database
and store it in hard rive.
Creating Databases The basic element of database creation is
fields/columns You have to identify the different concepts/object
and relations among concepts [in the system] For each, concept/object, you have to identify
fields Then create tables for each of the concepts (and
for relations sometimes) For each table define the fields/columns Identify data types and length for each
column/field and specify it when creating tables
Data Types for Fields Numeric
ByteBitIntLongDoublefloat
Data Types for Fields Text
TextCharVarchar
Date, DateTime Currency
Query Language: SQL Types
Select○ Selecting data by table fields
Parameter○ Query by filling information in dialog bixes
Crosstab○ Based on conditions
Action○ Delete, update, append
Sorting and Indexing Sorting
Is to arrange/sort data○ Low to high: Ascending
1, 2, 3, 4..100A ant boy cat
○ High to low: descending100,99,98....1Cat boy ant a
Indexing Create an index (information about the
position) of the data Indexing is not actually sorting the data but
keeping track of the locations of the data Index can keep track of the data
by ascending values or in descending values (of the data)
i.e. In index file there will be positions/addresses of the data, the addresses will be kept in the order of the values of the data
Indexing Data
4210050
Index of the data in ascending value of the data2, 1, 4, 3
Indexing Advantages
Can help to find the data faster when index by one field
Increases the performance of different database operations
DisadvantagesMore ram usedData entry can take time for multiple field based
indexWhen index with multiple fields, data editing can
take longer
Indexing vs Sorting
Relation Types Degree of relations
Unary -1Binary – 2Ternary – 3
Relation Types: among tables (concepts/objects in the system)One to oneOne to Many or Many to OneMany to Many
Use of Database for Government E-government E-governance
http://en.wikipedia.org/wiki/E-GovernanceE-Governance is the application of Information and
Communication Technology (ICT) for delivering government services, exchange of information communication transactions, integration of various stand-alone systems and services between Government-to-Citizens (G2C), Government-to-Business(G2B),Government-to-Government( G2G) as well as back office processes and interactions within the entire government frame work.
E-government
E-government http://en.wikipedia.org/wiki/E-Government E-Government (short for electronic government, also known
as e-gov, Internet government, digital government, online government, or connected government) is digital interactions between a government and citizens (G2C), government and businesses/Commerce (G2B), government and employees (G2E), and also between government and governments /agencies (G2G). Essentially, the e-Government delivery models can be briefly summed up as (Jeong, 2007):[1]
G2C (Government to Citizens) G2B (Government to Businesses) G2E (Government to Employees) G2G (Government to Governments) C2G (Citizens to Governments)
Data Security Data is important for an organization or
government or a person Data should not be able to be accessed
by unauthorized person Data when stored in the office or when
transferred over the internet, it should not be able to be accessed by unauthorized person such as hackers, or competitors
Methods to Provide Data Security Restrict access to the computer
(password protect) Restrict access to the database
(password protect) Use firewalls so that outsiders cannot
access While sending data encrypt(unreadbale
format) data
Data Encryption Changing/converting the data to unreadable
format while transferring Usually using some methods/algorithms
data are encrypted. Some encryption methods use keys Encryption Ingredients
Plaintext : text to be sentCiphertext : encryted textEncryption algorithm : method to encryptKey : used in encryption or decryption
Encryption Types Types
Secret-key encryptionPublic-key encryption
Secret-key encryptionSame key used for encryption and decryptionBoth sender and receiver know the key
Public-key encryptionSender: one key to encrypt : private to senderReceiver: another key to decrypt : private to
receiverOne more key, known to both
Encryption Methods/Algorithms Caesar code DES IDEA RSA
Further Study Encryption
http://www.salearningschool.com/searchResult.php?queryStr=encryption&submit=Search+Database
Encryption example○ http://www.salearningschool.com/displayArtic
le.php?table=Articles&articleID=1355 Encryption algorithms
http://www.cse-cst.gc.ca/its-sti/services/crypto-services-crypto/ca-ac-eng.html
Choosing encryption methods for SQL Serverhttp://technet.microsoft.com/en-us/library/m
s345262.aspx
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References DBMS Theory
http://www.salearningschool.com/index.php?table=Articles&categoryID=6&category=DBMS%20Theory
Database Systems http://www.salearningschool.com/index.php
?table=Articles&categoryID=2&category=Database%20Systems
MySQL DBMS http://www.salearningschool.com/searchRe
sult.php?queryStr=mysql&submit=Search+Database
Indexing vs Sorting http://docs.acl.com/acl/920/index.jsp?topic
=/com.acl.user_guide.help/data_analysis/c_sorting_versus_indexing.html
Have fun Guys!!!
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