Computer Science CentreUniversity of Indonesia

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Chapter 2

Database System Concepts and Architecture

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Evolution of computing

• Database has evolved since nearly every stage of computing, from:– mainframes, which are monolithic– Client-server– Web-based

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Data Models

• A collection of concepts used to describe the structure of a database– Data types– Relationships– Constraints– Etc

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Categories of Data Models

• Conceptual data models: high level• Physical data models: how data is

actually stored in a disk• Representational data models:

somewhere between those two… let’s see…

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Representational data model• Relational data model (our main

discussion in this class)• Network data model (uses directed

graphs)• Hierarchial data model (history…)• Object data model (this is new!)

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Database schemas• Schemas: description of the database, but not the

database itself!• Example of a schema diagram:

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• Not included in the schema diagram above:– Data types?– Relationships?– Constraints, such as “students in CS

major must take CS1310…”

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Database states

• Also called ‘snapshot’• After we define, generaly a database

is at the ‘empty state’• We get the ‘initial state’ after we first

load the database• Valid state is a state which satisfies

the structure and constraints in the schema

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Three Schema Architecture• Internal schema: describes the

physical storage structure of the database

• Conceptual schema: structure of the whole database for a community of users

• External schemas for user views

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In fo rm ationM anagem entR E S E A R C H G R O U P

Data Independence

• Logical data independence: we can change the conceptual schema without changing the application program

• Physical data independence: we can change the internal schema without changing the conceptual schema. It might be because file database must be reorganized for fine tuning.

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Database Languages

• Data definition language• View definition language• Data manipulation language

– High level: SQL, set-at-a-time processing

– Low level: VB, COBOL, record-at-a-time processing

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DBMS Interfaces

• Menu based interface• Forms based interface• Graphical user interface• Natural language interface, you can

ask, “Show me all the students with GPA > 3”

• Parametric interface, such as xBase

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Database utilities

• Loading utility, or importer• Backup utility, usually to tape• File optimizer or reorganizer• Performance monitoring:

fragmentation, load balancing, etc.

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Classification of DBMS

• Single user vs multi user• Centralized vs distributed• Price…!• OLTP support?• OLAP support (read page 842)

Computer Science CentreUniversity of Indonesia

In fo rm ationM anagem entR E S E A R C H G R O U P

Group Assignment

Comparative Study of Popular DBMS

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Which ones?Group 1 (Haswar,

Conna, Vicky)• MySQL• MS-SQL Server• FoxPro

Group 2 (Fitri, al-Harith, Avi)

• MySQL• MS-SQL Server• IBM DB2

Group 3 (Danu, Lia, Narpati)

• Oracle database• Postgres• Borland Interbase

Group 4 (Armand, Tia, Aryo)

• FoxPro• MS-Access• Informix

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What to look for

• Use theories in chapter 1 & 2!

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Deliverables

• Presentatoin (of course)• Due next week• Paper, submitted to the TAs: Elan

and Amir (again…!)