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2 Learning Outcomes Pada akhir pertemuan ini, diharapkan mahasiswa akan mampu : Mahasiswa dapat Menerangkan perbedaan DDL dan DML, View dan arsitektur multiuser

3 Outline Materi mengenal DDL dan DML penggolongan model data fungsi, komponen DBMS arsitektur multi-user sistem katalog

4 Chapter 2( lanjutan pert. 03) Database Environment Transparencies

5 Chapter 2 - Objectives u Distinction between DDL and DML. u A classification of data models. u Purpose/importance of conceptual modeling. u Typical functions and services a DBMS provide. u Software components of a DBMS. u Meaning of client–server architecture and advantages of this type of architecture for a DBMS. u Function & uses Transaction Processing Monitors. u Function and importance of the system catalog.

6 Database Languages u Data Definition Language (DDL) –Allows the DBA or user to describe and name entities, attributes, and relationships required for the application –plus any associated integrity and security constraints.

7 Database Languages u Data Manipulation Language (DML) –Provides basic data manipulation operations on data held in the database. u Procedural DML –allows user to tell system exactly how to manipulate data. u Non-Procedural DML –allows user to state what data is needed rather than how it is to be retrieved.

8 Database Languages u Fourth Generation Language (4GL) –Query Languages –Forms Generators –Report Generators –Graphics Generators –Application Generators.

9 Data Model Integrated collection of concepts for describing data, relationships between data, and constraints on the data in an organization. u Data Model comprises: –a structural part; –a manipulative part; –possibly a set of integrity rules.

10 Data Model u Purpose –To represent data in an understandable way. u Categories of data models include: –Object-based –Record-based –Physical.

11 Data Models u Object-Based Data Models –Entity-Relationship –Semantic –Functional –Object-Oriented. u Record-Based Data Models –Relational Data Model –Network Data Model –Hierarchical Data Model. u Physical Data Models

12 Conceptual Modeling u Conceptual schema is the core of a system supporting all user views. u Should be complete and accurate representation of an organization’s data requirements. u Conceptual modeling is process of developing a model of information use that is independent of implementation details. u Result is a conceptual data model.

13 Functions of a DBMS u Data Storage, Retrieval, and Update. u A User-Accessible Catalog. u Transaction Support. u Concurrency Control Services. u Recovery Services.

14 Functions of a DBMS u Authorization Services. u Support for Data Communication. u Integrity Services. u Services to Promote Data Independence. u Utility Services.

15 Components of a DBMS

16 Components of Database Manager (DM)

17 Multi-User DBMS Architectures u Teleprocessing u File-server u Client-server

18 Teleprocessing u Traditional architecture. u Single mainframe with a number of terminals attached. u Trend is now towards downsizing.

19 Teleprocessing Topology

20 File-Server u File-server is connected to several workstations across a network. u Database resides on file-server. u DBMS and applications run on each workstation. u Disadvantages include: –Significant network traffic. –Copy of DBMS on each workstation. –Concurrency, recovery and integrity control more complex.

21 File-Server Architecture

22 Client-Server u Server holds the database and the DBMS. u Client manages user interface and runs applications. u Advantages include: –wider access to existing databases; –increased performance; –possible reduction in hardware costs; –reduction in communication costs; –increased consistency.

23 Client-Server Architecture

24 Alternative Client-Server Topologies

25 Transaction Processing Monitors u Program that controls data transfer between clients and servers in order to provide a consistent environment, particularly for Online Transaction Processing (OLTP).

26 Transaction Processing Monitor as middle tier of a three-tier client-server architecture

27 System Catalog u Repository of information (metadata) describing the data in the database. u Typically stores: –names of authorized users; –names of data items in the database; –constraints on each data item; –data items accessible by a user and the type of access. u Used by modules such as Authorization Control and Integrity Checker.

28 Information Resource Dictionary System (IRDS) u Response to an attempt to standardize data dictionary interfaces. u Objectives: –extensibility of data; –integrity of data; –controlled access to data.

29 IRDS services interface

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