pert 2 sistem basis data

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thx to stopira!

  1. Discuss the concept of data independence and explain its importance in a database environment.
  2. To address the issue of data independence the ANSI-SPARC three-level architecture was proposed. Compare and contrast the three levels of this model.
  3. What is a data model? Discuss the main types of data model.
  4. Discuss the function and importance of conceptual modeling.
  5. Describe the types of facility you would expect to be provided in a multi-user DBMS.


Jawaban

1. A. Logical Data Independence

> Mengacu pada kekebalan skema eksternal terhadap perubahan dalam skema konseptual.

> Perubahan skema konseptual (misalnya penambahan / penghapusan entitas).

> Seharusnya tidak memerlukan perubahan skema eksternal atau penulisan ulang program aplikasi.

b. Physical Data Independence

> Mengacu pada kekebalan skema konseptual terhadap perubahan dalam skema internal.

> Perubahan skema internal (misalnya menggunakan file organisasi yang berbeda, struktur penyimpanan / perangkat).

> Seharusnya tidak memerlukan perubahan ke skema konseptual atau eksternal.

2. A. External Level

> Pengguna melihat database.

> Menggambarkan bahwa bagian dari database yang relevan dengan pengguna tertentu.

b. Conceptual Level

>Masyarakat membuka / view database

> Menggambarkan data apa yang disimpan dalam database dan hubungan antara data.

c. Internal Level

> Representasi fisik dari database di komputer.

> Menggambarkan bagaimana data disimpan dalam database.

3. Data Model kumpulan dari konsep konsep yang saling berhubungan kemudian dipadu menjadi satu yang kemudian digunakan untuk mendeskripsikan data, menghubungkan antara satu data dengan data yang lain, mencari serta meraparasi data rusak dalam sebuah orgnisasi.

4. - Conceptual modeling merupakan inti dari system, yang mendukung user dalam pemakaian software.

- lengkap dan akurat dalam pemberian keperluan data

- hasilnya sesuai dengan konsep.

5. The Data definition facility or Data Definition Language (DDL)

The data manipulation facility or Data Manipulation Language (DML)

The Data Control Facility (DCL)

pert 1 sistem basis data

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TwitThis

THX TO STOPIRA

  1. Describe each of the following terms;
    1. Data

Data adalah catatan atas kumpulan fakta. Data merupakan bentuk jamak daridatum, berasal dari bahasa latin yang berarti "sesuatu yang diberikan". Dalam penggunaan sehari-hari data berarti suatu pernyataan yang diterima secara apa adanya. Pernyataan ini adalah hasil pengukuran atau pengamatan suatu variable yang bentuknya dapat berupa angka, kata-kata, atau citra.

    1. Database

Shared collection of logically related data (and a description of this data), designed to meet the information needs of an organization.

    1. Database management system

A software system that enables users to define, create, and maintain the database and that provides controlled access to this database

    1. Database application program


A database application program is another program that actually uses the database to manipulate and represent data. For example, a forum system coded in PHP would use a database to store its users, posts, usage information, statistics, etc.

  1. Describe the approach taken to the handling of data in the early 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

  1. Describe the main characteristics of the database approach and contrast it with the file-based 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).

  1. Describe the five components of the DBMS environment and how they related to each other.

DS3-Figure 01-08

Data

Used by the organization and a description of this data called the schema.

Procedures

Instructions and rules that should be applied to the design and use of the database and DBMS.

People

Hardware

Can range from a PC to a network of computers.

Software

DBMS, operating system, network software (if necessary) and also the application programs.

  1. Describe the advantages and disadvantages of DBMSs.

Advantages of DBMSs

    1. Balanced conflicting requirements
    2. Improved data accessibility and responsiveness
    3. Increased productivity
    4. Improved maintenance through data independence
    5. Increased concurrency
    6. Improved backup and recovery services

Disadvantages of DBMSs

Complexity

Size

Cost of DBMS

Additional hardware costs

Cost of conversion

Performance

Higher impact of a failure

 

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