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Introduction HNDIT 11052 DBMS 1. Database Management Systems Module code HNDIT 11052 Module title Database Management Systems Credits2HoursLectures15.

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Presentation on theme: "Introduction HNDIT 11052 DBMS 1. Database Management Systems Module code HNDIT 11052 Module title Database Management Systems Credits2HoursLectures15."— Presentation transcript:

1 Introduction HNDIT 11052 DBMS 1

2 Database Management Systems Module code HNDIT 11052 Module title Database Management Systems Credits2HoursLectures15 GPAPractical45 Semester1Module type Common module 2

3 Aim & objective Build up essential skills required in planning, organizing, storage, retrieval of information in computer systems and skills required for managing / administrating small and mid range database systems. 3

4 Learning Outcomes At the end of the module the student will be able to: Describe the fundamental concepts in databases and data processing Analyze and systematically represent relationships in data records and perform data modeling Create, populate and manage relational databases in system Use query languages to populate, update and retrieve data from databases Implement basic security in database systems 4

5 Outline Syllabus An introduction to data processing and databases Database management systems Data analysis and Data modeling (ER diagrams and conceptual modeling) Relational models and normalizations Creating databases using GUI tools Query Languages (Standard Query language) Introduction to database security simple report creations. 5

6 Assessment & Weighting In class assignments and tutorials 25% Simple database design 25% End of semester examination Structured examination paper 50% 6

7 Why DBMS? Suppose we need to develop a Information system. How do we  store the data? (use file structures…)  query the data? (write programs…)  Update data safely? (write more programs…)  provide different views on the same data? (staff & students diffrent) ( prog…)  deal with crashes? (prog…) DBMS helps to above activities. 7

8 File based system Manual file Processing (paper based) – Time Consuming – Does not support large volumes of data File based Processing Database Management system 8

9 Library System Files File Based Processing Data Entry File Processing Data Entry File Processing ID001 Namemery Addresscolombo TelNo747374 Marks34 ID001 Namemery Addresscolombo TelNo747374 Books-bor 6 Student System Files Data Duplication 9

10 Library System Files File Based Processing Data Entry File Processing Data Entry File Processing ID001 Namemery Addresscolombo TelNo747374 Marks34 ID001 Namemery Addresscolombo TelNo747374 Books-bor 6 Student System Files Change request 10

11 Library System Files File Based Processing Data Entry File Processing Data Entry File Processing ID001 Namemery AddressKandy TelNo747374 Marks34 ID001 Namemery Addresscolombo TelNo747374 Books-bor 6 Student System Files Inconsistent Data Address Change request 11

12 Problem in file based system Inconsistent data Data duplication Security Inflexibility Limited data sharing Excessive program maintenance How do we resolve these problems? 12

13 Solution is DBMS DBMS is solution to rectify file based processing problems 13

14 Data Entry & Reports Data Entry & Reports DBMS Students Library Application Programs App. Programs Database Database Processing stno Name address 001 mery colombo ……………. Change Request

15 Data Entry & Reports Data Entry & Reports DBMS Students Library Application Programs App. Programs Database Database Processing stno Name address 001 mery Kandy ……………. Change Request

16 DATABASE DEFINITION A shared collection of logically related data designed to meet the information requirements of an organisation. 16

17 Database Management System (DBMS) A software system that enables users to define, create and maintain the database and which provides controlled access to the database. 17

18 History of Database Systems 1950s and early 1960s: – Data processing using magnetic tapes for storage Tapes provide only sequential access – Punched cards for input Late 1960s and 1970s: – Hard disks allow direct access to data – Network and hierarchical data models in widespread use – Ted Codd defines the relational data model Would win the ACM Turing Award for this work IBM Research begins System R prototype UC Berkeley begins Ingres prototype – High-performance (for the era) transaction processing 18

19 History (cont.) 1980s: – Research relational prototypes evolve into commercial systems SQL becomes industry standard – Parallel and distributed database systems – Object-oriented database systems 1990s: – Large decision support and data-mining applications – Large multi-terabyte data warehouses – Emergence of Web commerce 2000s: – XML and XQuery standards – Automated database administration – Increasing use of highly parallel database systems – Web-scale distributed data storage systems 19

20 Database models Early Types of DBMS – Hierarchical – Network Current Generation – Relational Advanced Systems - Object Based 20

21 What is a Database System? Database System = Database + DBMS A Database is – A large, integrated collection of data – Models (represents) a real-world enterprise. Entities (e.g., students, courses) Relationships (e.g., Mary takes CS123) A Database Management System (DBMS) is – A software package designed to store and – Manages databases easily and efficiently. 21

22 Common Uses of Databases Try to think why each of these need to use a database: – Supermarkets – Insurance – Credit Cards/Banking – Libraries – Travel Agents – Universities 22

23 Examples: DBMS MSAccess MySQL – freeware (Windows & Unix) McKoi – freeware, Java based. Oracle SQL Server – Microsoft product – we use in this course Any other ? Common features: –Relational model –SQL as query language –Server-client architecture 23

24 Advantages of using a DBMS  Minimal data redundancy  Efficient data access  Data integrity and security  Data administration  Concurrent access, recovery from crashes  Reduced application development time 24

25 Disadvantages  Complexity  Additional Hardware costs  Experts – Specialised personnel  Higher impact of failure Simple applications may not need DBMS at all 25

26 Main Characteristics of the Database Approach Self-describing nature of a database system: A DBMS catalog stores the description of the database. –called meta-data). –allows the DBMS software to work with different databases. Database Raw dataMeta data Systems Catalog 26

27 Main Characteristics of the Database Approach Insulation between programs and data: Called program-data independence. Allows changing data storage structures and operations without having to change the DBMS access programs. 27

28 Data independence  Application programs are independent of data representation and storage details.  The structure of data files is stored in the DBMS catalog separately from the access programs. E.g. a file access program may be written in such a way that it can access only STUDENT records of the structure. First Year SLIIT-200628

29 Main Characteristics of the Database Approach Data Abstraction: A data model is used to hide storage details and present the users with a conceptual view of the database. 29

30 Main Characteristics of the Database Approach Support of multiple views of the data: Each user may see a different view of the database, which describes only the data of interest to that user. stnonamegpaprogramregDatepayment 100Mira3.8BSc. IT2005 - JANFull 200Janet2.5BSc IS2004- JANHalf 300Ravi2.7M.Sc IT2006- JANFull stnonamegpa 100Mira3.8 200Janet2.5 300Ravi2.7 stnoregDatepay 1002005 - JANFull 2002004- JANHalf 3002006- JANFull Lecturer view Administrative staff view

31 Questions? 31


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