2 Learning Outcomes Pada akhir pertemuan ini, diharapkan mahasiswa akan mampu : Mahasiswa dapat Menerangkan perbedaan antara sistem database dengan sistem file based
3 Outline Materi aplikasi/penerapan database sehari-hari karakteristik file-based masalah dan keterbatasan file-based
4 Chapter 1 Introduction to Databases Transparencies
5 Chapter 1 - Objectives u Some common uses of database systems. u Characteristics of file-based systems. u Problems with file-based approach. u Meaning of the term database. u Meaning of the term Database Management System (DBMS).
6 Examples of Database Applications u Purchases from the supermarket u Purchases using your credit card u Booking a holiday at the travel agents u Using the local library u Taking out insurance u Using the Internet u Studying at university
7 File-Based Systems u Collection of application programs that perform services for the end users (e.g. reports). u Each program defines and manages its own data.
9 Limitations of File-Based Approach u 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. u Duplication of data –Same data is held by different programs. –Wasted space and potentially different values and/or different formats for the same item.
10 Limitations of File-Based Approach u Data dependence –File structure is defined in the program code. u Incompatible file formats –Programs are written in different languages, and so cannot easily access each other’s files. u Fixed Queries/Proliferation of application programs –Programs are written to satisfy particular functions. –Any new requirement needs a new program.
11 Database Approach u 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. u Result: –the database and Database Management System (DBMS).
12 Database u Shared collection of logically related data (and a description of this data), designed to meet the information needs of an organization. u System catalog (metadata) provides description of data to enable program–data independence. u Logically related data comprises entities, attributes, and relationships of an organization’s information.
13 Database Management System (DBMS) u A software system that enables users to define, create, and maintain the database and that provides controlled access to this database.
14 Database Approach u Data definition language (DDL). –Permits specification of data types, structures and any data constraints. –All specifications are stored in the database. u Data manipulation language (DML). –General enquiry facility (query language) of the data.
15 Database Approach u Controlled access to database may include: –A security system. –An integrity system. –A concurrency control system. –A recovery control system. –A user-accessible catalog. u A view mechanism. –Provides users with only the data they want or need to use.
16 Views u Allows each user to have his or her own view of the database. u A view is essentially some subset of the database.
17 Views u 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.
19 Components of DBMS Environment u Hardware –Can range from a PC to a network of computers. u Software –DBMS, operating system, network software (if necessary) and also the application programs. u Data –Used by the organization and a description of this data called the schema.
20 Components of DBMS Environment u Procedures –Instructions and rules that should be applied to the design and use of the database and DBMS. u People
21 Roles in the Database Environment u Data Administrator (DA) u Database Administrator (DBA) u Database Designers (Logical and Physical) u Application Programmers u End Users (naive and sophisticated)
22 History of Database Systems u First-generation –Hierarchical and Network u Second generation –Relational u Third generation –Object Relational –Object-Oriented
23 Advantages of DBMSs u Control of data redundancy u Data consistency u More information from the same amount of data u Sharing of data u Improved data integrity u Improved security u Enforcement of standards u Economy of scale
24 Advantages of DBMSs u Balanced conflicting requirements u Improved data accessibility and responsiveness u Increased productivity u Improved maintenance through data independence u Increased concurrency u Improved backup and recovery services
25 Disadvantages of DBMSs u Complexity u Size u Cost of DBMS u Additional hardware costs u Cost of conversion u Performance u Higher impact of a failure
26 > Dilanjutkan ke pert. 02 Database environment