1 Chapter 1 Introduction to Databases Transparencies Last Updated: Pebruari 2010 By M. Arief Updated by RSO Feb

Course Introduction ► TI SKS ► Learning Objective:  Understand about DBMS concept  Capable to design DBMS ► Marking Composition:  30% UTS, 40% UAS, 10% Individual works, 10% group work, 10% lab work ► Intro to Lecturer 2

Group Works ► Max 10 groups in the class ► Choose your leader ► Leader bring Connolly book to the class ► Group discussion in the class ► Group project outside class ► Arrange seats for group discussion ► Tidy up & clean up the class 3

4 What problems you might think?

5 Chapter 1 - Objectives 1. Some common uses of database systems. 2. Characteristics of file-based systems. 3. Problems with file-based approach. 4. Meaning of the term database. 5. Meaning of the term Database Management System (DBMS).

6 Chapter 1 - Objectives 6. DBMS Approaches. 7. Major components of the DBMS environment. 8. Personnel involved in the DBMS environment. 9. History of the development of DBMSs. 10. Advantages and disadvantages of DBMSs.

7 1. Database Applications ► Purchases from the supermarket ► Purchases using your credit card ► Booking a holiday at the travel agents ► Using the local library ► Taking out insurance ► Using the Internet ► Studying at university

8 2. File-Based Systems ► Collection of application programs that perform services for the end users (e.g. reports). ► Each program defines and manages its own data.

9 File-Based Processing

3. FBS problems ► Make a list of problems that may happened on File Based System! ► Sales Files  Client(ClientNo,fName,iName,address,telpNo,prefType,MaxRent)  PrivateOwner(OwnerNo,fName,iName,address,telpNo)  PropertyForRent(PropertyNo,street,city,postcode,Type,Rooms,Rent, OwnerNo) ► Contract Files  Client(ClientNo,fName,iName,address,telpNo)  PropertyForRent(PropertyNo,street,city,postcode,Rent)  Lease(LeaseNo,PropertyNo,ClientNo,Rent,PaymentMethod,Deposit, Paid,RentStart,RentFinish,Duration) 10

11 Limitations of File-Based Approach ► Separation and isolation of data  Each program maintains its own set of data.  Users of one program may be unaware of potentially useful data held by other programs. ► Duplication of data  Same data is held by different programs.  Wasted space and potentially different values and/or different formats for the same item.

12 Limitations of File-Based Approach ► Data dependence  File structure is defined in the program code. ► Incompatible file formats  Programs are written in different languages, and so cannot easily access each other’s files. ► Fixed Queries/Proliferation of application programs  Programs are written to satisfy particular functions.  Any new requirement needs a new program.

13 4. Database ► Shared collection of logically related data and a description of this data, designed to meet the information needs of an organization. ► System catalog (metadata) provides description of data to enable program–data independence. ► Logically related data comprises entities, attributes, and relationships of an organization’s information.

14 Entity-Relationship Diagram

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

16 6. Database Approach ► Arose because:  Definition of data was embedded in application programs, rather than being stored separately and independently.  No control over access and manipulation of data beyond that imposed by application programs. ► Result:  the database and Database Management System (DBMS).

17 DBMS Provides: ► No Control?  Lots of Controlled access to database may include: ► A security system. ► An integrity system. ► A concurrency control system. ► A recovery control system. ► A user-accessible catalog. ► Not Independent?  DBMS provide a view mechanism. ► Provides users with only the data they want or need to use.

18 Views ► Allows each user to have his or her own view of the database. ► A view is essentially some subset of the database.

19 Views ► Benefits include:  Reduce complexity;  Provide a level of security;  Provide a mechanism to customize the appearance of the database;  Present a consistent, unchanging picture of the structure of the database, even if the underlying database is changed.

FBS problems Solved ► Solve FBS problems by composing these files! ► Sales Files  Client(ClientNo,fName,iName,address,telpNo,prefType,MaxRent)  PrivateOwner(OwnerNo,fName,iName,address,telpNo)  PropertyForRent(PropertyNo,street,city,postcode,Type,Rooms,Rent, OwnerNo) ► Contract Files  Client(ClientNo,fName,iName,address,telpNo)  PropertyForRent(PropertyNo,street,city,postcode,Rent)  Lease(LeaseNo,PropertyNo,ClientNo,Rent,PaymentMethod,Deposit, Paid,RentStart,RentFinish,Duration) 20

21 Database Management System (DBMS)

22 DBMS also Provides: ► Data definition language (DDL).  Permits specification of data types, structures and any data constraints.  All specifications are stored in the database. ► Data manipulation language (DML).  General enquiry facility (query language) of the data.

23 7. Components of DBMS Environment

24 Components of DBMS Environment ► Hardware  Can range from a PC to a network of computers. ► Software  DBMS, operating system, network software (if necessary) and also the application programs. ► Data  Used by the organization and a description of this data called the schema.

25 Components of DBMS Environment ► Procedures  Instructions and rules that should be applied to the design and use of the database and DBMS. ► People

26 Database Design: The Paradigm Shift ► Which one is yours? why? ► The organization has to think of the application first and the data second. or ► The organization has to think of the data first and the application second.

27 8. Roles in the Database Environment ► Data Administrator (DA) ► Database Administrator (DBA) ► Database Designers (Logical and Physical) ► Application Programmers ► End Users (naive and sophisticated)

28 DA and DBA ► The Data Administrator (DA) is responsible for the management of the data resource including database planning, development and maintenance of standards, policies and procedures, and conceptual/logical database design. ► The Database Administrator (DBA) is responsible for the physical realization of the database, including physical database design and implementation, security and integrity control, maintenance of the operational system, and ensuring satisfactory performance of the application for users.

29 Logical and Physical DB Designer ► Logical DB Designer is concerned with identifying the data (entities and attributes), the relationship between the data, and the constraints on the data. They must have a thorough and complete understanding of the organization’s and its business rule.  Conceptual database design  Logical database design ► Physical DB Designer decides how the logical database design is to be physically realized. This involves:  Mapping log. DB des. Into a set of tables and integrity constraints  Selecting specific storage structures and access methods for the data to achieve good performance  Designing any security measures required on the data. ► Highly dependent on the target DBMS ► Logical DB Designer: What, Physical DB Designer: How

30 9. History of Database Systems ► First-generation  Hierarchical and Network ► Second generation  Relational ► Third generation  Object Relational  Object-Oriented

Individual Home Work ► Make a list of descriptions of DBMS advantages and Disadvantages from Connolly Book Chapter 1