ER normalization

I have givened an ER Diagram :

ERD in the above, there are 2 that confusion can lead to an error occurs, namely:

1. On the relationship between the BAGIAN and the PROYEK does not have a clear cardinality.

2. There is a ternary relationship have on the relationship.

So i repair the ER, and this my project.

Mapping of ER Diagram above :

1 NF and 2NF Normalization

• pegawai

this table decomposit to three table

• bagian

this tabel, decomposit to two table

• kerja

• proyek
• tanggungan
  

normalizatiom mapping

1. If the relation 1-N in the primary key (1) move to (N) and vice versa applies.
2. If the relationship M-N will be created a new table with the primary key of each entity will be became the primary key in the new table.
3. If the relationship 1-1 then choose higher cardinality to put primary key for a foreign key in relation table .
4. If the dependent relationships of the primary key table dependent primay key derived from the mother entity.

DATABASE NORMALIZATION

Database Normalization

Normalization is required because of the redundancy relations, not good relations. The main reason is the possibility of "update anomalies" (when the insert, delete, update) because can impact on the data inconsistencies, The reason is other waste storage space (hard disk),Normalization process is the establishment of  database structure so the ambiguity can be removed. Normalization stage, starting from the most mild (1NF) to most stringent (5NF). Normalization is usually only up to the level of 3NF or BCNF because already sufficient to generate the table-a table of good quality.

Why normalization needed?

• Optimization table structures
• Increase the speed
• Eliminate income data the same
• More efficient use of storage media
• Reduce redundancy
• Avoiding anomalies (insertion anomalies, deletion anomalies, update anomalies).
• Improved data integrity

Criteria database tabel

• If there is decomposition table, it must be guaranteed safe decomposition it. That is, after the table is described / decompositioned a new table-table, the table-table can generate a new table with the same exact.
• Maintain dependence on the functional changes in data (Dependency preservation).
• Does not violate Boyce-Code Normal Form (BCNF)

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

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.
• Symbols used are to represent the functional dependency.

Notation : A -> B

A and B are attributes of a table. A means of determining the functional B or B depends on A, if and only if there are 2 rows of data with the same value of A, then B is also the same value

Notation : A ->/ B or A x-> B

It is the opposite of the previous notation

Example 

Functional Dependency:

NRP -> Nama

Mata_Kuliah, NRP -> Nilai

Non Functional Dependency:

Mata_Kuliah -> NRP

NRP -> Nilai

• Functional Dependency from the value table :
  

NRP -> Nama

• Because for each value NRP the same, then the value of the same nama.
  

{Mata_Kuliah, NRP } -> Nilai

• Because the value of attributes depending on the NRP and Mata_Kuliah together. In another sense  Mata_Kuliah for the NRP and the same, they also rated the same, because Mata_Kuliah and the NRP is a key (is unique).
  

Mata_Kuliah ->/ NRP

NRP ->/ value

Normal Form

Normal form is a condition (using the FD and key) that determines whether a scheme relationships meet certain criteria. There are several normal forms based on a number of criteria:

1. Primary keys (1NF, 2NF, 3NF)
   
2. All Candidate Keys (2NF, 3NF, BCNF)
3. Multivalued dependencies (4NF)
4. Join dependencies (5NF)

1NF (First Normal Form)

A table on the form said to be normal if I did not reside in the unnormalized form of a table, where there is a kind of field multiplication and field that allows a null (empty) 1NF is not allowed on the:

1. Attribute values, many (Multivalued attributes).
2. Attribute a composite or a combination of both.
3. nested relations.

for more details I give you example

• the tables above does not meet the requirements 1NF.
  
• Decomposition becomes:

mahasiswa tabel

hobi tabel

2NF (Second Normal Form)

Normal form 2NF met in a table if it meets the form of 1NF, and all the attributes than the primary key, have a full Functional Dependency on primary key. A table does not meet 2NF said, if there are attributes that Functional Dependency are only partial (only depending on the part of the primary key). If there are attributes that have no dependence on the primary key, then the attributes must be moved or removed.

1. Functional dependence X -> Y , said full if it is said to delete an attribute A from X means that Y is no longer dependent functional.
2. Functional dependence X -> Y , said partial if a delete attribute A from X means that Y is functionally dependent.
3. Relation scheme R in the form 2NF if every non-primary key attribute A Î R depend on the full functional primary key R.

Example

Does not meet 2NF, because (NIM, CodeMk) is regarded as the primary key whereas:

{NIM, KodeMk} > NamaMhs

{NIM, KodeMk} > Alamat

{NIM, KodeMk} > MataKuliah

{NIM, KodeMk} > Sks

{NIM, KodeMk} > Nilai

The table needs to decomposition to become some table eligible 2NF.

Functional dependency it as follows:

fd1 {NIM, KodeMk} > Nilai 

fd2 NIM > {NamaMhs, Alamat}

fd3 KodeMk > {MataKuliah, Sks}

So that :

fd1 (NIM, KodeMk, Nilai) > Table of Nilai

fd2 (NIM, NamaMhs, Alamat) > Table of Mahasiswa

fd3 (KodeMk, MataKuliah, Sks) à Table of MataKuliah

3NF (Third Normal Form)

Normal form 3NF fulfilled if the form meets 2NF, and if there are no non-primary key attribute that has a dependence on non-primary key attributes of the other (transitive dependencies).

Example

Table following students eligible 2NF, 3NF, but does not meet

Because the table above there are still non-primary key attribute (ie, Kota and Provinsi), which has a dependence on non-primary key attributes of the other (ie KodePos), namely:

KodePos > {Kota, Provinsi}

So that the table in the decomposition needs to be:

Mahasiswa (NIM, NamaMhs, Jalan, KodePos)

KodePos (KodePos, Provinsi, Kota)

Boyce-Codd Normal Form (BNCF)

Boyce-Codd Normal Form constraint has a stronger form of the third Normal. To be BNCF, relations must be in the form of first Normal and forced each of the attributes depends on the function in the super key attributes.

In the example below there is a relationship seminar, Primary Key is NPM + Seminar.

Students may take one or two seminars. Each seminar requires 2 each of the students and led by one of the 2 seminar. Each leader can only take one seminar course. NPM in this example and the Seminar show a Preceptor.

Seminar Relationship 

Example

Seminar relations is a Third Normal Form, but not BCNF because Code Seminar is still dependent on the function Pembimbing, if any Pembimbing can only teach a seminar. Depending on the seminar is not a super key attributes such as required by BCNF. But relations Seminar should be parsed into two namely:

Relations Seminar is a form of Third Normal, but not BCNF Seminar Code because the function depends on the preceptor, if every preceptor can only teach a seminar. Depending on the seminar is not a super key attributes such as required by BCNF. But relations Seminar should be parsed into two namely :

4 NF and 5 NF (Normal Form of the Fourth and Fifth)

Relations in fourth normal form (4NF) if the relation in BCNF and does not contain a lot of dependence values. To remove the dependency of many values from a relation, we divide the relationship into two new relations. Each relation contains two attributes that have a lot of relationship value.

Relations in fifth normal form (5NF) deal with the property called the join without any loss of information (lossless join). Fifth normal form also called the 5 NF PJNF (projection join normal form). The case is very rare and appear difficult to detect in practice.

DATABASE AND ER-DIAGRAM

DATABASE

Database is structured group of records (magnetic disk, optical disk, or other secondary store).

Database can indicate a group of interconnection data for venture (company, government institution).

Database is a collection of data from a related one with the other stored in the computer and necessary software to manipulate. Or, organizing the collection of data related to each other to facilitate activities to obtain information.

DATABASE MANAGEMENT SYSTEM (DBMS)

Collection / database combined with software-based database applications. Application programmed are used to access and maintain databases The main purpose DBMS is to provide an environment that is efficient and easy to use, with draw and storage of data and information

BIT, BYTE, AND FIELD

Bit is a part of contain smallest data value 0 or 1. Byte is a collection of same bit.

1 byte = 8 bit.

Field is a group of same byte, in database used by attribute.

ATTRIBUT/FIELD

It is the nature or characteristics of an entity that provides provide detail on these entities. within a relationship can also have attributes

Example attributes:

Lecturer: NIP, NAME, ADDRESS

STUDENTS: NIM, NAME, ADDRESS

CAR: NOMOR_PLAT, COLOR, TYPE, CC

TYPE OF ATTRIBUT

Single vs. multivalue

In the single type can only be filled at most only one nila

In the multivalue types can be filled with more than one value with the same type of

Atomic vs. composition

Atomic can not be divided into the attributes of smaller

The composition is a combination of several attributes of a smaller

Derived attribute

attribute value can be derived from the value of other attributes, such as age attributes resulting from the date of birth attribute

Null Value attribute

Attributes that have no value to a record

Mandatory attribute Value

Attribute must have a value, usually this is a primary key in an entity

RECORD / TUPLE

It is a line of data in a relationship. Consists of the set of attributes where the attribute-attribute-attribute is to inform each other entity / relationship fully

KEY

In a collective entity, or entity type, between one entity with another entity must be distinguished. Make how an entity is unique? We need to find an attribute that can be deference.

For example, for the employee, SSN is unique because no two people have the same SSN. For the company, the name can be unique as there is no company that has the same name with another company.

For the payment slip, may have two attributes as pembeda, eg date and time.

Attribute whose value is called a unique key attribute .. An entity can have one key attribute, can 

also better than one

TYPES OF KEY

Super Key is one or more attributes of a table that can be used to identify entity/ record of the table are unique (not all attributes can be superkey). 

Candidate Key is a super key with minimal attributes. Candidate must not contain a key attribute of the table so that the other candidate key is certain superkey but not necessarily vice versa. 

Primary Key 

One of the key attributes of the candidate can be selected / specified a primary key with the three following criteria: 

1. Key is more natural to use as reference 

2. Key is more simple 

3. Key is guaranteed unique 

Alternate Key is an attribute of the candidate key is not selected to be primary key.

 

Foreign Key is any attribute that points to the primary key in another table. Foreign key will be going on a relationship that has cardinality one to many (one to many) or many to many (many to many). Foreign key is usually always put on the table that point to many.

 

External Key is a lexical attribute (or set of lexical attributes) that values are always identify an object instance

ERD (ENTITY RELATIONSHIP DIAGRAM)

Entity relationship is a network that uses the order of the data stored in the abstract of the system. Entity-relationship model consists of elements of the entity and entity-relationship between these entities.

Differences between DFD and of ERD DFD represent a function network model to be executed by system, while ERD represent data network model emphasizing at structure and relationship data.

ELEMENTS OF ERD

Entity

In the ER Diagram Entity is described with the form of a rectangle. Entity is something that exists in the real system and the abstract where the data stored or where there are data.

Relationship

ER diagram on the relationship can be described with a lozenge. Relationship is a natural relationship that occurs between entities. In general, the name given to the verb base making it easier to do readings relationships. Relationship Degree is the number of entities participating in a relationship. Degree which is often used in the ERD.

Attribute

is the nature or characteristics of each entity and relationship

Cardinalitas

tupel indicates the maximum number that can be associated with entities on the other entity

There are 3 kardinalitas relations, namely :

One to One: Level one to one relationship with the one stated in the entity's first event, only had one relationship with one incident in which the two entities and vice versa.

One to Many or Many to One: Level one to many relationship is the same as the one to many depending on the direction from which the relationship is reviewed. For one incident in the first entity can have many relationships with the incident on the second entity, if the one incident in which two entities can only have a relationship with one incident in which the first entity.

Many To Many: if any incident occurs in an entity has many relationships with other entities in the incident.

Relationship degree

• Unary Relationship model is the relationship between the entity originating from the same entity set.
• Binary Relationship model is the relationship between 2 entities.
• Ternary Relationship is a relationship between the instance of 3 types of entities are unilateral.

Data Flow Diagram

What is Data Flow Diagram (DFD)
Data flow diagram illustrate how data is processed by a system in terms of inputs and outputs, describe the distribution of the modules in the system to a smaller .Easy to understand the less the field to understand the computer system that will be done. Data flow diagrams can be used to provide a clear representation of any business function. The technique starts with an overall picture of the business and continues by analyzing each of the functional areas of interest. This analysis can be carried out to precisely the level of detail requird. The technique exploits a method called top-down expansion to conduct the analysis in a targeted way.

How to Draw Data Flow Diagram
Numbering level on DFD
Context Diagram

• Consists of a process and describe the scope of a system
• It is the highest level of the DFD that describes the entire system to the input of the system and outpur
• The system is limited by Boundary (depicted by broken lines)
• No storage (storage)
• Firstly, draw and name a single process box that represents the entire system.
• Next, identify and add the external entities that communicate directly with the process box. Do this by considering origin and destination of the resource flows and data flows.
• Finally, add the resource flows and data flows to the diagram.
  

Context diagram guidlines
In drawing the context diagram you should only be concerned with the most important information flows. These will be concerned with issues such as: how orders are received and checked, with providing good customer service and with the paying of invoices. Remember that no business process diagram is the definitive solution - there is no absolute right or wrong.

Zero Diagram

• Describe the process of the DFD
• Provide views on the overall system in which, showing the main function or process that is, the flow of data and entity eskternal
• At this level of data storage possible
• For processes that do not detailed again on the next level then added the symbol '*' or 'P' at the end of the process
• Input and output balance (balancing) between 0 to diagram context diagram should be maintained
  

Detailed Diagram

• Decompose a process that is in the diagram zero level or above
• In the one level there should be no more than 7 units and the maximum of 9, when more should be done in the decomposition
• Each process in the DFD must have a specification process
• At the top level method is used to describe the process can use a sentence with descriptive
• On a more detailed level, namely on the bottom (functional primitive) requires specification of a more structuredspecification process will be the guideline for the programmer to make this program (coding)
• Methods used in the specification process: the process of disintegration in the form of a story, decision table, decision tree
  

Foreign entity

• Something that is outside the system, but it provides data in the system or to provide data from the system
• symbolicby the notation
• External entity not part of the system including
• Naming:

1. The name of the form of noun
2. 2. Terminal may not have the same name except the same objeknya
   

Flow Data

• It is a place flowed the information
• described the straight line that connects the components of the system
• Flow data is shown with the direction arrows and the name on the flow of data that flows
• Flow data flow between processes, data storage and data flow indicates that the form of data input for the system
• Guidelines of the name:

1. Name of the flow of data that consists of some words associated with the flow lines connect
2. No flow data for the same and the name should reflect its content
3. The flow of data that consists of several elements can be expressed with the group element
4. Avoid using the word 'data' and 'information' to give a name to the flow of data
5. Wherever possible the complete flow of data is written

• Terms of others:

1. Name of the flow of data into a process may not be the same as the name of the data flow out of the process
2. Data flow into or out of data storage does not need to be given a name if: Flow of data simple and easy to understand, Flow of data describing all the data items
3. There can be no flow of data from the terminal to the data storage, or vice versa because the terminal is not part of the system, the relationship with the terminal data storage must be through a process
   

Process

• The process is what is done by the system
• The process can process data flows or data entry into the flow of data out
• The transform function of one or more of data input into one or more of the output data in accordance with the desired specifications
• Each process has one or more inputs and produce one or more output
• The process is also often called bubble
• Guidelines of the process:

1. Name of the process consists of a verb and noun, which reflects the function of the process
2. Do not use the process as part of the name of a bubble
3. May not have some process that has the same name
4. The process should be given a number. Order number wherever possible to follow the flow of the process or sequence, but the sequence number does not mean that the absolute is a process in chronological order
   

Data Storage

• Data storage is a storage place for data that exists in the system
• Symbolic by a pair of parallel lines or two lines with one side open side
• The process can retrieve data from or provide data to the database
• Guidelines of the name:

  1. The name should reflect the data storage
  2. When his name more than one word must be marked with the number
     

Data Dictionary
Working to help the system to interpret the application in detail and organize all elements of the data used in the system precisely so that the system analyst and have a basic understanding of the same input, output, storage and process

• At the analysis stage, the data dictionary is used as a means of communication between the systems analyst with the
• At the system design, data dictionary is used to design input, reports and databases
• Flow data on the global DAD, further details can be seen in the data dictionary
• load the data dictionary as follows:

1. Name of data flow: must note that readers who need further explanation about a flow of data can find it easily
2. Alias: alias or other name of the data can be written when there is
3. Forms of data: used to segment the data dictionary to use when designing the system
   
4. Flow data: indicates from which data flows and where the data
5. Description: to give an explanation of the meaning of the data flow
   

Balancing in the Data Flow Diagram

• Flow of data into and out of a process must be the same as the flow of data into and out of the details of the process on the level / levels below
• Name of the data flow into and out of the process must match the name of the flow of data into and out of the details of the process
• Number and name of an entity outside the process must be equal to the number of names and entities outside of the details of the process
• The issues that must be considered in the DFD which have more than one level:
  

1. There must be a balance between input and output of one level and next level
2. Balance between level 0 and level 1 at the input / output of stream data to or from the terminal on level 0, while the balance between level 1 and level 2 is seen on the input / output of stream data to / from the process concerned
3. Name of the flow of data, data storage and terminals at each level must be the same if the same objeknya

Restrictions in the DFD

• Flow data may not be from outside the entity directly to other outside entities without going through a process
• Flow data may not be from the savings directly to the data to outside entities without going through a process
• Flow data may not be saving the data directly from the savings and other data without going through a process
• Flow of data from one process directly to the other without going through the process of saving data should / be avoided as much as possible
  

Data Flow Diagram Symbol

INITIAL OBSERVATION AND REQUIREMENT ANALYSIS

Sistem ivestigation concept

Gap between sistem purpose and real condition of system

Gap between sistem purpose and real condition of system, causes by the failure of the system, the analyst should conduct an investigation before taking action to improve the system. With the investigation, an analyst will be more problems and understand system flow more depth, even detect the problem is known but the problem still describe the size of the course.

Report of unreal problem detection

• Purpose to ideal
  

The purpose to ideal, can make  dificult to realize the system destination and the rport of system investigation will be untarget.

• The flaws resources and  manne
  

The lack of  resource  and manne cause information colectting can not be accurate

• Measuring System not accurate
  

The lack of measuring sistem can make an error report of investigation system.

•  System purpose are dated
  

System purposes out of date make a report of investigation system didnt appropriate whit the function 

• Different between idle system and temporary system
  

The diferent between idle system and temporary system can make dificult to used the system cause have a crucial diference. 

 

Problem solving:

1. Accurate investigation
   
2. Get a ideal  consensus system
   
3. Expand some alternative
   
4. Choose the best alternative

Investigation Purpose to indicate the real problem

Constraint in Investigation System

some problem when doing the investagation system like ;

1. Time

System investigation need alot of times, so use the time by efficiance.

2. Cost

Cost of investigation related  of time and length the investigative activities.

  3. Knowledge

lack of project knowlege will impact on the results of investigations that are less  mature or complete.

  4. Politic

In indonesian this conditon usually happen, didnt condusif the politic situation make all about birocration will be complecated and investigation activities will needed alot times.

5. Interference 
intervene or control activities in investigas that will disrupt or cause a disruption.

Recommendation

Result of investigation is a recommendation which is filled with:

1. Never take any action

This is mean when there is no problems find in system we can’t take any actions.

  2. System maintenance

System maintenance needs to maintenance small problems like when job description not runs very well. So we must solve that problem and after we solve it we must maintenance.

  3. Increase  user ability

User ability must be increase for hightest user skill, and problem solving will be faster than before.

  4. Totally consider to system modification

system modification needed, if the system out of date and didnt appropriate the uses.

  5. Put problem into the development system plan

put problem into the development system plan can make a problem solving planing and quickly  to finished.

 

Investigation tactic

 Why need some tactic?

  1. find all the problem

there is we must  find all about our problem

  2. find out the reason

there is we must find a reason of our problem.

3. find out the best solution

there is we must find the sollution to solve our problem

Investigation tactics need to all element system be able to receive offer solution without interrupt their activities.

 

Several tactics:

1. listen suggestion from system agent
   
2. don’t give first solution
3. consideration several stories from system agent about same cases
4. notice the logical inconsistent problem

 

Investigation Technique

• Direct:
  

1. Questioner
2. Question and Answer
3. Monitoring

 

• Non-direct:
  

1. Current procedure
2. Learn the document
3. Sample
4. Tabular

 

Description of the system at this time

Determine the performance of the system at this time will have difficulty when
company does not have a standard performance measurement system.
Unfortunately, companies tend not to update 
documentation systems that are running. Therefore, analysts improve document system problems during the investigation.
Description of the system include a clear explanation at this time:
a. Inputs 
b. Outputs 
c. Files 
d. Data elements 
e. Transaction volume document and action
f. Data flow diagrams

 

Analysis Requirement

Requirement analysis phase is the intensive interaction between the analyst system with the user community the system, where the development team system shows the expertise to get the responses and confidence the user, so get a good participation.
Is working hard to get user agreements about their needs from an information system, as they may the failure of the previous information system.

Target which wish reached

1. Explaining system completely
2. Depicting ideal information system
3. Bringing ideal information system to condition in this time by paying attention to resource constraint
4. Giving motivation to wearer confidence into system development

Method

1. Question And Answer
2. Kuisioner
3. Observation
4. Procedure analyse
5. Document perception

Resource constaraint

1. Time
2. Money
3. Membership
4. Technological
5. Eksternal Factor 

Requirements analysis document

• Analysis instruction.
  

Relation with the final wearer, perception process, problem of data collecting, Relationships with end users. Analyze the records, forms and reports,Observation process,Analyzing the methods used,Problems in data collection.

• Requirements of the user.
  

Requirement in fact, Report requirement, requirement of training and new system influence, What are the actual needs,Reporting needs,Training needs,The influence of the new system.

• Constraint system.
  

Explain the constraints of time, cost, expertise, technology and factor external,Realistic system.

• Documentation.
  

Instrument data collection,Consensus statistics,The logical flow of data and physical,Initial element in the data dictionary.

 

Generating Systems Alternatives

How do I approach the condition of the system at this time with the condition of the ideal system?

create alternative to solve the information system problem and find thebest alternative to applying accordance with wisely

 

Strategy selection

1. Distributed versus centralized processing

Change information decision from centralized data processing to decentralized end user responsibility center.

  2. Integrated versus dispersed database

System planner must consider what kind of incoming data to database and incoming to file.

 

3. Surround Strategy of System Development

Environs are important strategy in case overtake company because information system from other company possible different with company at moment.

 

Selection tactic

Do before operational planner selection started. If we can make some tactic before doing operational planner, we can choose the best tactic to solve the problem.

Operational planner selection

Planner selection is able categorize into:

• Input
  

1. Online Vs Off Line Data Entry
2. Keyed Vs Machine Readable Data Entry
3. Centralized Vs Decentralized Data Entry

• Processing
  

1. Batch Vs Real-time record update
2. Sequential Vs Direct Access to records
3. Single Vs Multiple User update of records

• Output
  

1. Traditional Vs Turn Around Documents
2. Structured Vs Inquiry based reports

 

Selecting the Proper System

Equal tactic: equivalent system based on cost and profit relatively. There is 3 system, A called more excellent with other system if:

1. A have low cost then B and their profit same.
2. A have low cost then B and A produce profit more than B.
3. A and B have same cost but produce of profit A more than B.

 

Several comparative method system

1. Break Even point analysis
2. Payback period
3. Discounted payback period
4. Internal rate of return

 

Cost category

1. Hardware
2. Software
3. People
4. Suppliers
5. Telecommunications
6. Physical sites 

Cost details

Equal system information cost by means of life system, analyst projection several cost change for future and 3 cost model information system that is Linear, Exponential and Step Function.

 

Information system cost happen in one time and be able happen continuous.

• Information system cost happening in one time that is on-time cost and development cost while system development consist.
• Information system cost happening continuous there are recurring cost with operational cost while cost happen at information system operated every day.

Information System Factor

Qualitative factor direct to best information system there are:

1. reduce mistake state
2. reduce time to solve mistake
3. reduce perceptive time from alternative workstation
4. increase time to supplying information
5. raise system security
6. increase update from active record
7. raise user satisfied

Representation Learning System

1. shortly presentation
2. reduce technically details
3. represented clearly with visual tools
4. if use model, use tools like laptop so more informative
5. pushed profit from information system proposal with several alternative agree with company condition

 

Advanced Decision or Not

• If company decision to develop the system then information department will doing advanced process there is system design process
• If the other way then System Development Life Cycle (SDLC) will stopped.
• Often find problem with studying system and usually top management will asked to do re-processing with studying system.
• Model will explained several continuous state and sometime information department will create decision to repeat state before explain studying system.
• With alternative, decision to repeat a state System Development Life Cycle (SDLC) before or not called Go – No –Go Decision.