basic concep

ERD QUIZ

2009-05-03T07:08:00.000-07:00

ERD quiz

Is given by the following ERD :

Settlement:

From the ERD, there are some explanations that are less about the cardinality relationship between the BAGIAN entity with PROYEK entity and between PROYEK entities to the ternary. So I assume that the relationship between the BAGIAN entity with PROYEK entity are 1 : N where one can have the many projects and one project is owned by only one part only. For PROJECT entities to ternary, I use cardinality N where an employee can have many projects and one project is owned by an employee only.

At the PEGAWAI entity, there is composite attribute that is address attribute. In the making of 1NF is each of the attributes may not be composite, So to write the ALAMAT attribute which is a fraction of the written that address attribute is ALM1 attribute and KDPOS attribute.

From ERD diagram above there is 2 error, that is:

Ø Between table BAGIAN and PROYEK No cardinality .

Ø To determine foreign key between table PEGAWAI and BAGIAN on relation PIMPIN.

Ø No relation from table PROYEK to ternary, because table PROYEK has have relation KERJA with table PEGAWAI.
So, I try to improve ERD as following:
ERD

• I give cardinality between table BAGIAN to table PROYEK with relation 1 to N (one to many).

• I give participation from table BAGIAN to table PEGAWAI the relation is total, in order to I can determine which one table that get foreign key from relation PIMPIN.

• I remove relation between table PROYEK to ternary, because table PROYEK has have relation KERJA with table PEGAWAI.

MAPPING
NORMALISASI
1NF and 2NF

For table TANGGUNGAN and KERJA don’t need to normalization, because that tables don’t have primary key.
For the 3NF normalization. First, determine attribute from above which have transitive dependency, that is:

NORMALIZATION

2009-04-26T04:54:00.001-07:00

Database Design Process

There are some processes that must be done to design a database, that is:

Ø Gathering user needs / business

Ø Develop the E-R model based on user needs / business

Ø Convert E-R Model to set the relation (table)

Ø Normalization of relations, for the anomaly

Ø To implement the database for each table to create relationships that have been in the normalization

Database Normalization

Normalization process is the establishment of the database structure so that most of the ambiguity can be removed. Normalization is done at the design stage, before the database is implemented. Purpose to avoid update anomalies. To find out how to do normalization, we must first understand the concept of functional dependency and key.

The purposes normalization :

Ø Optimization table structures

Ø Increase the speed

Ø Eliminate income data the same

Ø More efficient use of storage media

Ø Reduce redundancy

Ø Avoiding anomalies (insertion anomalies, deletion anomalies, update anomalies).

Ø Improved data integrity

A table is good (efficient) if following the criteria:

Ø If there is decomposition (decomposition) table, then the decomposition will be guaranteed safe (Lossless-Join Decomposition). That is, after the table is described / in the decomposition into a new table-table, the table-table can generate a new table with the same exact.

Ø Maintain the functional dependence on the change data (Dependency preservation)

Ø No violate Boyce-Code Normal Form (BCNF)

If the three criteria (BCNF) can not be connected, at least the table does not violate the Normal Form of the third stage (3rd Normal Form / 3NF).

Why normalization is required because of the redundancy relations, not relations of good ?

That because possibility of "update anomalies" (when the insert, delete, update) because can impact on the data inconsistencies

The way to Handle anomaly are :

Ø Anomaly in the handle by programming language used to create the application database. Designer should note this anomaly and to tell a programmer.

Ø Anomaly does not handle the system, but submitted to the operator to be careful in making modifications, inserts and deletes. It is human error risk.

Ø Anomalies be avoided, with ways to secure the normalization.

Denormalization

Denormalization is a reverse process of normalization, ie, combine several relations, brought to normal form of a lower.

Functional Dependency (FD)

Functional dependency (abbreviated FD) is a restriction that comes from the meaning of attributes and relationships between attributes. Functional Dependency attributes describe the relationship in a relationship. An attribute said functionally dependant on the other, if we use the value attribute to determine the value of the other attributes.

First Normal Form - 1NF

Ø Functional Dependency dari tabel nilai

– Nrp à Nama

Karena untuk setiap nilai Nrp yang sama, maka nilai Nama juga sama

– {Mata_kuliah, NRP} à Nilai

Karena attribut Nilai tergantung pada Mata_kuliah dan NRP secara bersama-sama. Dalam arti lain untuk Mata_kuliah dan NRP yang sama, maka Nilai juga sama, karena Mata_kuliah dan NRP merupakan key (bersifat unik).

– Mata_kuliah à NRP

– NRP à Nilai

BENTUK NORMAL PERTAMA (First Normal Form - 1NF)

A table said to be normal I if it not in the unnormalizet table form, in that procces ther is same field duplication and able to happen the null field.

There is will be not :

Ø Multivalued attribute

Ø Composite attribute or combination of both.

Ø Domain value must be atomic value.

For example :

Ø The tables above aren’t eligable 1NF

Second Normal Form - 2NF

Ø Normal form 2NF eliged in a table after to elig primary 1NF form, and all attributes beside primary key, and have Functional Dependency at primary key.

Ø A table is not eliged 2NF if there is Functional Dependency attribute.

Ø If there is a attribute that have not dependency to the primary key, so that attribute must be deleted.

Third Normal Form (3NF)

Third normal form (3NF) goes one large step further:

Ø Meet all the requirements of the second normal form.

Ø Remove columns that are not dependent upon the primary key.

Fourth Normal Form (4NF)

Finally, fourth normal form (4NF) has one additional requirement:

Ø Meet all the requirements of the third normal form.

Ø A relation is in 4NF if it has no multi-valued dependencies.
Remember, these normalization guidelines are cumulative. For a database to be in 2NF, it must first fulfill all the criteria of a 1NF database.

References:

ER Ngurah Agus Sanjaya. Slide Part 6 - NORMALISASI.
Siti Aminah. Slide Review_Normalisasi_untuk_Vcon_7_des.

BASIS DATA DAN ER-DIAGRAM

2009-04-19T06:28:00.000-07:00

DEFINISI BASIS DATA

Definisi basis data:

Basis data adalah Sekumpulan data yang tersimpan dalam magnetic disk, optical disk atau penyimpanan sekunder lainnya

DATABASE MANAGEMENT SYSTEM

¨ merupakan general purpose software yang digunakan untuk:

– Mendefinisikan

– Mengkonstruksi

– Memanipulasi

Kumpulan/gabungan database dengan perangkat lunak aplikasi yang berbasis database

Program-program aplikasi ini digunakan untuk mengakses dan memelihara database

Tujuan utama DBMS adalah menyediakan suatu lingkungan yang mudah dan efisien untuk penggunaan, penarikan dan penyimpanan data dan informasi

Contoh-contoh DBMS yang ada adalah:

· Microsoft Acces, ORACLE, PostgreSQL, MySQL, SQL Server, dll.

BIT, BYTE, FIELD

Bit à merupakan bagian data terkecil yang berisi nilai 0 atau 1

Byte à kumpulan dari bit-bit yang sejenis

Ukuran 1 Byte = 8 Bit

Field à sekumpulan byte-byte yang sejenis, dalam basis data digunakan istilah atribut

ATRIBUT/FIELD

Merupakan sifat atau karakteristik dari suatu entitas yang menyediakan menyediakan penjelasan detail tentang entitas tersebut

Suatu relasi juga dapat memiliki atribut

Contoh atribut:

MAHASISWA: NIM, NAMA, ALAMAT

MOTOR: NOMOR_PLAT, WARNA, JENIS, CC

TIPE-TIPE ATRIBUT

Single vs multivalue

Single à Each entity has a single atomic value for the attribute.

Contoh Single value Atribut : NIM pada tabel mahasiswa

Multivalue à An entity may have multiple values for that attribute.

Contoh Multivalue atribut : Hobby(mancing, film, music), Persyaratan(cantik, muda, berbakat).

Atomic vs komposisi

Atomic à tidak dapat dibagi ke dalam atribut yang lebih kecil

Contoh : NIM, NIP, nama panggilan.

Komposisi à merupakan gabungan dari beberapa atribut yang lebih kecil

Contoh : Nama(nama depan, tengah, belakang), alamat(jalan, kota, kode pos)

TIPE-TIPE ATRIBUT (2)

Derived Attribute

atribut yang nilainya dapat dihasilkan dari nilai atribut lain, misal à umur yang dihasilkan dari atribut tanggal lahir

Null Value Attribute

Atribut yang tidak memiliki nilai untuk suatu record

Contoh : atribut yang bukan merupakan key

Mandatory Value Attribute

Atribut yang harus memiliki nilai

Contoh : atribut yang bersifat sebagai key.

RECORD/TUPLE

Merupakan suatu baris data dalam suatu relasi

Terdiri dari kumpulan atribut-atribut dimana atribut-atribut tersebut saling berhubungan untuk menginformasikan entitas/relasi secara lengkap

Contoh : satu record mewakili satu data/informasi -- > nim, nm_mhs, alamat.

ENTITAS/FILE

Entitas “sesuatu” atau “obyek” di dunia nyata yang dapat dibedakan dari “sesuatu” atau “obyek” yang lainnya. Entitas pada umumnya memiliki sejumlah property dimana property ini dapat digunakan untuk membedakan suatu entitas dengan entitas lainnya. Property ini kemudian disebut sebagai atribut dari entitas tersebut.

File merupakan kumpulan dari record yang sejenis dan mempunyai elemen yang sama, atribut sama namun berbeda-beda data valuenya.

Tipe File

Dalam pemrosesan aplikasi, file dapat dikatagorikan sbb:

– File Induk

– File Transaksi

– File Laporan

– File Sejarah

– File Pelindung

– File Kerja

DOMAIN

Domain merupakan kumpulan dari nilai-nilai yang diperbolehkan untuk berada dalam satu atau lebih atribut. Setiap atribut dalam suatu basis data relasional didefinisikan sebagai suatu domain

KUNCI ELEMEN DATA

Key adalah elemen record yang dipakai untuk menemukan record tersebut pada waktu akses atau bisa juga digunakan untuk mengidentifikasi setiap entity/record/baris.

JENIS-JENIS KEY

Superkey merupakan satu atau lebih atribut dari suatu tabel yang dapat digunakan untuk mengidentifikasi entityty/record dari tabel secara unik (tidak semua atribut dapat menjadi superkey)

Cadidate Key adalah super key dengan atribut minimal. Candidate key tidak boleh berisi atribut dari tabel yang lain sehingga candidate key sudah pasti superkey namun belum tentu sebaliknya.

Primary Key

Salah satu atribut dari candidate key dapat dipilih/ditentukan menjadi primary key dengan tiga kriteria sbb:

1. Key tersebut lebih natural untuk digunakan sebagai acuan

2. Key tersebut lebih sederhana

3. Key tersebut terjamin keunikannya

JENIS-JENIS KEY (2)

Alternate Key adalah atribut dari candidate key yang tidak terpilih menjadi primary key.

Foreign Key merupakan sembarang atribut yang menunjuk kepada primary key pada tabel yang lain. Foreign key akan terjadi pada suatu relasi yang memiliki kardinalitas one to many (satu ke banyak) atau many to many (banyak ke banyak). Foreign key biasanya selalu diletakkan pada tabel yang mengarah ke banyak.

Akan terjadi pada suatu relasi yang memiliki kardinalitas one to many atau many to many

External Key merupakan suatu lexical atribut (atau himpunan lexical atribut) yang nilai-nilainya selalu mengidentifikasi satu object instance.

ERD (ENTITY RELATIONSHIP DIAGRAM)

ERD adalah suatu model jaringan yang menggunakan susunan kata yang disimpan dalam sistem secara abstrak.

Perbedaan antara DFD dan ERD

DFD merupakan suatu model jaringan fungsi yang akan dilaksanakan oleh sistem

ERD merupakan model jaringan data yang menekankan pada struktur dan relationship data

Biasanya digunakan oleh profesional sistem untuk berkomunikasi dengan pemakai eksekutif tingkat tinggi dalam perusahaan yang tidak tertarik pada pelaksanaan operasi sistem sehari-hari, namun lebih kepada :

Data apa saja yang diperlukan untuk bisnis mereka?

Bagaimana data tersebut berelasi dengan data lainnya?

Siapa saja yang diperbolehkan mengakses data tsb?

ELEMEN-ELEMEN ERD

ENTITY

Pada ER Diagram Entity digambarkan dengan bentuk persegi panjang. Rntity adalah sesuatu yang ada dalam sistem nyata maupun abstrak dimana data tersimpan atau dimana terdapat data.

Relationship

Pada ER Diagram relationship dapat digambarkan dengan sebuah bentuk belah ketupat. Relationship adalah hubungan alamiah yang terjadi antara entitas. Pada umumnya diberi nama dengan kata kerja dasar sehingga memudahkan untuk melakukan pembacaan relasinya.

Relationship Degree

adalah jumlah entitas yang berpartisipasi dalam satu relationship. Derajat yang sering dipakai dalam ERD.

Atribut

adalah sifat atau karakteristik dari tiap entitas maupun relationship

Digambarkan dengan symbol oval

Gambar diatas adalah atribut dengan nama “Nama”

Kardinalitas

menunjukkan jumlah maksimum tupel yang dapat berelasi dengan entitas pada entitas yang lain

Derajat relationship

Unary Relationship

adalah model relationship yang terjadi antara entity yang berasal dari entity set yang sama.

Binary Relationship

adalah model relationship yang terjadi antara 2 entitas.

Ternary Relationship

merupakan relationship antara instance dari 3 tipe entitas secara sepihak.

KARDINALITAS

Terdapat 3 kardinalitas relasi yaitu

– One to One : Tingkat hubungan satu ke satu dinyatakan dengan satu kejadian pada entitas pertama, hanya mempunyai satu hubungan dengan satu kejadian pada entitas yang kedua dan sebaliknya.

– One to Many atau Many to One : Tingkat hubungan satu ke banyak adalah sama dengan banyak ke satu tergantung dari arah mana hubungan tersebut dilihat.Untuk satu kejadian pada entitas pertama dapat mempunyai banyaj hubungan dengan kejadian pada entitas yang kedua, jika sebaliknya satu kejadian pada entitas yang kedua hanya dapat mempunyai hubugan dengan satu kejadian pada entitas yang pertama.

– Many To Many : terjadi jika setiap kejadian pada sebuah entitas mempunyai banyaj hubungan dengan kejadian pada entitas lainnya.

NOTASI (DIAGRAM E-R)

Notasi simbolik dalam diagram ER adalah

1. Persegi panjang menyatakan himpunan entitas

2. Lingkaran menyatakan atribut

3. Belah Ketupat menyakatan himpunan relasi

4. Garis sebagai penghubung antara himpunan relasi dengan himpunan entitas dan Himpunan Entitas dengan atributnya

General Observation System Developments

2009-03-08T08:58:00.000-07:00

GENERAL OBSERVATION SYSTEM DEVELOPMENTS

System cleyelopment is to pile up a new system to change the old system entirely or repairing the system that already exist before. The important thinies in the information system development is:

1. There problem that to appear in the old system.

a. Problem in the old system causing it can’t operated like wanted one.

b. Grow of organization that causing we must to pile up a new system.

2. To reach up portunities in the information speed competition market or efisiency of the time is a factor of success or not the strategy and plans that already piled up to the change.

3. There are directives not meaning the system is developed by the command from the leader but organization competition.

The aims of system information development:

To prevent the problems on this contecs is mean that we must do the reparation on problems that already exist on the old system to make a new system that can repairing the problems and also to fill the need of organization grow.
To reach the change we must can improving the system in the system in the it’s information speed or efficiency of the time for the success of organization in strategy and the plans that already piled up.
To fulfill the intruction thet gived. Can fulfill what organization needs from new system to compete with other organization.

The increase performance on the new system work. That meke more effevtive. The ob system can be see from the throughput and response time. Throughput is the total of job that can do in an sure time. Response time is the range of the time between first transaction with second transaction. Improvitation economy of profit and dagrease the production cost.Improving control,of control to detec and repair the mistake and not fair that will heaven and already heaven.

The principle of system development.

Processing the system development we must know some process,such as:

System for management.

After developed the information of this system will be used by management.

Sytem that already developed is high capital infestement.

This system is developed by very big capital infestement

- to minimize the lost opportunity cost.

- Cost benefit analyse and cost effectiveness analyse.

System need the people that already have the skill.

In this vector the important is human.The human not must have formal education.

Work stages

System development life cycle is consist of the work and job of the work that must be do.

System development not must straight.this mean stages can be not straight,but can be do together.
Don’t fear to cancel the project,to decise to continue or cancel the project must evaluated carefully.
System documentation,must made in the processing time since that system development is still and process,because this documentation can a pair from result of any part of system development.

System Development Life Cycle

Waterfall Model

Waterfall Model explanation:

1. Requirement, in process requirement this is systems analysis does need collecting process from customer and or top management either from aspect area also business strategy, towards system and or desirable application.

2. Design, in this stage us does systems analysis process, fitur that need, need from application that be made good to also the application. Beside that, here we also begin to make design plan from system, like interfaces delegation, the data structure, the architecture, and as it.

3. Implementation, implementation process has been continuation from where did we begin to implementation design that made to into program codes that be read by engine language.

4. Verification, process verification here same like testing process towards system and or application that made. This process focus in internal logic from application that made, as certain that any line coding checking. Beside that here we also have done testing process towards possibility towards errors from system that made.

5. Maintenance, process maintenance here be repair process and maintenance towards system that made. Repair process here done when application and or system that made to experience error after to customer so that must necessary repair process towards system and or caused by development towards an OS so that application must be repaired again to be update.

Iteratif Model

Iteratif model explanation:

Iteratif Model here same with waterfall model, here found same processes, like requirement, design, implementation, and testing (verification).

1. Initial planning, be beginning planning process and or beginning ideas to make a system.

2. Planning, planning here be a thinking that ripe towards system that be made.

3. Requirement, same like in process requirement waterfall model, here systems analysis does need collecting process from customer and or management on towards system and or desirable application.

4. Analysis and design, in this stage us does systems analysis process, fitur everything that need, need from application that be made good to also the application. Beside that, here we also begin to make design plan from system, like interfaces delegation, the data structure, the architecture, and as it.

5. Implementation, implementation process has been continuation from where did we begin to implementation the design that made to into program codes that be read by engine language.

6. Deployment, process deployment here purpose has been distribution process towards system that made, in our meaning distributes before hand system to society before do testing so that we know our system deficit.

7. Testing, process testing here we have done testing towards system and or application that made. This process focus in internal logic from application that made, ascertain that any line coding checking. Beside that here we also have done testing process towards possibility towards errors from system that made.

8. Evaluation, process evaluation here be repair process, maintenance and renewal towards system that made. Repair process here done when application and or system that made to experience error after to customer so that must necessary repair process towards system. Maintenance process and renewal be done caused by development towards an OS so that application must be repaired again to update. In renewal process here will return to do process planning, data collecting (requirement), analysis system and design, implementation, deployment, testing and return again to evaluation. if there development again, so this cycle be repeated again.

Spiral Model

Spiral model explanation:

Spiral model is divided to be 4 task areas, that is:

1. Determine objectives, in this process us will determine what will be made system, either from also output from it system.

2. Identify and resolve risk, here we do identification process, planning and analyze risks may be happen. In identification process and planning, we must define before hand resource, time precision, and other related information project with system that we shall make. While in risk analysis process here we do analysis towards risks may be happen, between management or technical.

3. Development and test, in process development and test this is us do engineering process, construction and testing towards system that be made. In engineering process and construction, we do process coding to make a application. While in testing, we do testing process towards system or application that we have made.

4. Plan the next iteration, here we do iteration process for plan next and or evaluation in the event of request from customer in order to change towards system or application.

In this spiral model, when is process revolutionary begun, system engineer team moves clockwise surround spiral begun from the kernel. Spiral rotation first track produces development from product spesification. Spiral rotation furthermore may be worn to develop a prototype, and progressively develop system version will be increase. Each track that pass planning region produces to setting in project plan.

Approach System Development

Found several approach to develop system, that is:

1. Classical approach vs structured approach (looked at from methodology that used).

2. Piecemeal approach vs system approach (looked at from target that be achieved).

3. Bottom-Up approach vs Top-Down approach (looked at from manner determines need from system).

4. Total-system approach vs modular approach (looked at from manner develop it).

5. Great loop approach vs evolutionary approach (looked at from technology that used).

System Development Approach

Classical Approach vs Structured Approach

- Classical approach is opponent of structured approach. Classical approach methodology is system development by following the stages in this life cycle system.

- Classical approach is also known as traditional approach. This is an approach in system development that following stages of the life cycle without use the remarkable equipments and techniques.

Problems in classical approach is :

1. Softwere developing is more dificull because the shortage of equipment and techniques in developing the system and result of the softwere developing procces is become not objective and dificul to do.

2. Carity cost of the system will more expensive.

3. The mistake opportunity is high.

4. System success ratio is small.

5. Trouble ratio is big in approach system.

Structured Approach

Because many problems in classical approach, the need of better system develop is start to feel needed. But until now, still many people not know that only follow the life cycle will not make information system develop will success. Structured system develop concept is not a new concapt. The ansambling company technique and sircuit model of electronic equipment are two example of this concept that used in the many industries.

Great-loop approach vs evolutionary approach

- Great-loop approach :

a. Developing the system together using good technology.

b. High risk and spend a lot cost.

- Evolutionary approach :

a. Use the great technology for some application.

b. Developed for follow the need.

c. Small cost and can follow technology development.

System develop methodology

In system develop, methodology is needed, they are unites of method, procedures, concept of job, regulations, ponstulats, that used in a science, arts or other disciplines.

Method is a systematic technique to finish anything. By following method and procedures that methodology give, system develop is hoped will be able to finished and successful. Procedures stages of problems answer known as alogarithme.

Three type of methodology develop are :

1. Functional decomposition : Decide system become subsystem. For example : HIPO, stepwise refinement, iterative stepwise refinement, information hiding.

2. Data-oriented : Seeing on data characteristic that proccesed.

- Data-flow oriented : modules with data element type.

- Data-strucplease explain the meaning of methodology, method and algorithmture oriented : Input and Output structures.

3. Prescriptive : Usually prepared by softwere maker company, and that ones

in this methodology category are ISDOS, PLEYSYS, PRIDE and SDM/70

Tool In System Development

Tools that used in a methodology usually shaped a picture or diagram or graph. Graph formed system development tools, that is:

? HIPO diagram

? Data flow diagram

? Structured chart

? SADT diagram

? Warnier/Orr

Beside graph formed tools, found several graph formed tools has general likes Chart. Chart can classified as follows:

1. Chart to describe activity (activity charting).

? System flowchart

? Program flowchart that can be in the form of:

? Program logic flowchart

? Detailed computer program flowchart

? Paperwork flowchart or form flowchart

? Database relationship flowchart

? Process flowchart

? Gantt chart

2. Layout charting

3. Staff relatioanship charting

? Working distribution chart

? Organization chart

Technique In System Development

Techniques that can be used in development system, that is:

1. Project management technique, that is CPM (Critical Path Method) and pert (program evaluation and review technique). This technique is used for project scheduling.

2. Fact finding techniques, that is technique that can be used to gather data and find facts in study existing system, that is:

? Interview

? Observation

? Questionnaire

? Sample collecting

3. Cost-effectiveness analysis or cost benefit analysis

4. Technique to run meeting

5. Technique inspection/walkthrough.

Analysis System And Programmer

Analysis system is one who analyze system to study and identify that problems and determine user needs system. Programmer is one who write program code to a certain application based on has planned to get up that made by system analyst.

Function and or task from a analyst system that is as mediator or liaison between system user with programmer. Analyst system must realize right second knowledge differ about the computer technology to can communicate with programmer and knowledge about application that be developed so that can communicate with system user.

Knowledge And Skill That Need System Analyst

Found several vast eruditions and skill that must has by a system analyst, that is:

1. Knowledge and skill about data processing technique, computer technology and computer programming.

? Technical skill that must has belong skill in tool use and technique for application software development with skill in use computer.

? Technical knowledge that must has cover erudition about hardware, data communication technology, computer languages, os, utilities, and another.

2. Knowledge about business in general.

This knowledge be wanted so that system analyst can communicate with system user.

3. Knowledge about quantitative method.

System analyst use many quantitative methods in build application models, like dynamic programming, regresion, network, decision tree, trend, simulation and other as it.

4. Trouble-shooting skill.

System analyst must has ability to put complex troubleshoots that is faced by business, divide problem into parts, analyze it and then must can return composed to be a system can overcome troubleshoots.

5. Communication skill delivers staff.

System analyst must has ability to hold communication either through tongue or article. This skill is need in interview, presentation, meeting and report maker.

6. Skill builds connection delivers staff.

Human is factor critical insides system and human character one with another differ, so that need a skill to build connection delivers staff.