Personality Test

My Personality Test Result

This test is based on Carl Jung and Isabel Briggs Myers typological approach to personality. Taking up this test also excites me. Even though I knew myself, I cannot deny the fact that I want to discover something new about my personality. “ENFJ” – this is the result I’ve got after taking up the examination. This result is equivalent to a MENTOR according to the site (http://www.mypersonality.info/personality-types/).

An article from http://www.personalitytest.net/types/descriptions/enfj.htm discussed that ENFJs optimistic outlook toward social relationships is a burden to them at times. When external conflicts affect a group, the ENFJ is likely to assume responsibility. Their ability to empathize then turns into a liability. ENFJs, when over-identifying with the pain of others, will loose sight of their own concerns and interests. Their idealism can also be the cause of some distress when their assumptions are unable to weather the winds of reality. Fantasized relationships rarely translate into reality and even the best charismatic leader encounters unexpected resistance. Like all NFs, ENFJs will disassociate themselves from stressful situations in an effort to protect their sense of well-being and togetherness. The ENFJ, however, will repress the unpleasant side of life only to have to face it later in an intensified form when it explodes from its hiding place. It can manifest itself as fits of anger, sudden outbursts, or emotional explosions. Often the ENFJ's body will reflect pent-up stress by manifesting various physical symptoms that will erupt unexpectedly.

           

      According to a site http://www.personalitypage.com/html/ENFJ.html, portrait of ENFJ refers to a GIVER.  (Extraverted Feeling with Introverted Intuition).

This site talk about lots of various characteristic of a ENFJ person. So, I just pick some characteristics that really describes me. I know that these characters describes who  am I. Here is the list for those characteristics mentioned:

- people-focused individuals

- live in the world of people possibilities

- They understand and care about people

- main interest in life is giving love, support, and a good time to other people

-  focused on understanding, supporting, and encouraging others

- make things happen for people

- They get under people's skins and get the reactions that they are seeking

- avoid being alone   (This is true! :) )

- fill their lives with activities involving other people (Like!)

- they're likely to interact with others on their own level, in a chameleon-like manner. For me, this means that I can easily mingle with other people. ("madaling makisalanuha sa iba")

- have definite values and opinions which they're able to express clearly and succinctly

- expressive and open (Sometimes, i love to share my ideas and opinions)

- People love ENFJs. They are fun to be with, and truly understand and love people. They are typically very straight-forward and honest (super Agree! I actually smile when I read these sentences. )

- They are usually good at anything which captures their interest.

- have a tendency to be fussy

- They get excited about possibilities for the future

- basically happy people when they can use that gift to help others

- they enjoy their plans more than their achievements

I also listed below some of the characteristics of a ENFJ person that I'm not sure if I possess that characteristic or not. Here are those characteristics: 

- excellent people skills

- have a special talent for bringing out the best in others

- they have the ability to make people do exactly what they want them to do

- use their power over people to manipulate them

- tend to define their life's direction and priorities according to other people's needs, and may not be aware of their own needs

- their strongest interest lies in being a catalyst of change in other people

- They are generally bright, full of potential, energetic and fast-paced.

- do very well in situations where they can inspire and lead others

- but may become easily bored and restless with the present

- They're very loyal and trustworthy once involved in a relationship.

          While reading these information, I didn't expect that a ENFJ person like me has a special talent of bringing out the best in others. I'm also surprise that ENFJ can do very well in situation where they can inspire and lead others and they are generally bright, full of potential, energetic and fast-paced.

ENFJ Career Matches

ENFJs are often happy with the following jobs which tend to match well with the Mentor/Visionary personality. 

·         Accountant/Auditor    

·         Artist

·         Administrator                  

·         Actor

·         Administrative Assistant

·         Banker/Economist

·         Consultant                         

·         Computer Specialist       

·         Career Counselor

·         Church Worker

·         Diplomat

·         Designer

·         Events Coordinator         

·         Editor                                   

·         Engineer                             

·         Facilitator

·         Human Resources

·         Homemaker

·         Librarian

·         Musician

·         Nurse

·         Occupational Therapist

·         Psychiatrist

·         Psychologist/Counselor

·         Project Manager              

·         Politician

·         Social Worker

·         Senior Manager

·         Scientist

·         Sales Representative

·         Trainer

·         Teacher/Professor

·         Technical Specialist          

·         Writer

      The highlighted career are careers that I want in my life. I'm amazed that in this list of career, ACCOUNTANT and ENGINEER are included. One of these two careers is my choice before when i'm still a high school student. :) But now, as a BSIT student, I want to choose between ADMINISTRATOR, TECHNICAL SPECIALIST, EDITOR, SYSTEM CONSULTANT, PROJECT MANAGER or even COMPUTER SPECIALIST.   :)

AUTISM-SPECTRUM QUOTIENT

Autism-Spectrum Quotient or AQ Test Reaction

            Autism-Spectrum Quotient or AQ Test is a test to measure the extent of autistic traits in adults. It is not a 100% accurate test but it undergoes studies at Cambridge's Autism Research Centre. As stated on the site (http://www.wired.com/wired/archive/9.12/aqtest.html), the first major trial using the test, the average score in the control group was 16.4. Eighty percent of those diagnosed with autism or a related disorder scored 32 or higher. The test is not a means for making a diagnosis, however, and many who score above 32 and even meet the diagnostic criteria for mild autism or Asperger's report no difficulty functioning in their everyday lives.

            When I took the test online, I got the score of 20. According to a site (http://aq.server8.org/), a result of 20 means normal. Knowing this result, I laugh and said to myself, “Yehey! I’m a normal person, hahaha”. At first, I thought that I’m a little bit autistic because me and my close friends (namely:  Jove, April, Claire, Klemfer and Rodjjell) are somewhat out of this world at some times. We have our own world sometimes, acts like a child, someone told us that our age is not appropriate for our age and we really observed that we easily laugh just because of simple little things (“mababaw na kaligayahan”).

            This kind of examination is exciting, you can’t predict the result and what ever be the result, it will surely surprise you. Based on my own experience, taking the test really excites me. It is interesting. But I realized that the results didn’t have a big impact in me. It doesn’t change my trait, behavior or attitude. Nothings change. It only adds information. Moreover, deep inside there’s no reason for me to rely on the result just to test if I’m an autistic or not. Because as of now, I know my capacity and I’m aware on my trait and behavior. I’m not saying that the AQ Test is useless or nonsense. I’m only saying that in my part, it has no impact for me and it doesn’t change me. I don’t know if others have the same opinion with me and I’m just sharing my reaction and thoughts about this test. Maybe, this test is important for those people who have questions regarding on their behavior.  :)  

 

Reflection about "The Pirates of the Silicon Valley"

    The movie is about the competition between Steve Jobs, the co-founder of Apple Computers(played by Noah Wyle) and Bill Gates, co-founder of Microsoft (played by Anthony Michael Hall). The movie shows the contribution of these two gentlemen in the development of the two computer companies during their college life. Moreover, the film shows  the rivalry  of Jobs and Gates and their ideas towards the  development of the personal computers.

     In the movie, Jobs and his buddy Steve Wozniak invented a computer and  with that they’ve earn money. Soon , the Apple Company became a booming company. Meanwhile, Bill Gates and his buddy Paul Allen bluff their way into creating an OS for the newfangled machine – the Altair. Then they bluffed their way into licensing DOS to IBM. Soon, Gates and Allen also earned money but not as much as Apple Company. Apple steals the Graphical User Interface from Xerox’s PARC labs, then Microsoft steals it from Apple. For me, that’s the idea why the movie was entitled as “The PIRATES of the Silicon Valley”. Silicon Valley refers to the area of the Northern California where computer development of 1980’s and 1990’s surged. 

      The story of the movie doesn’t only revolved in the works of the two gentlemen but also in their lives. Steve Jobs is adopted and he faces many difficulty issues because of his lack of self-identification as a result of the adoption. He sees himself as a creative and imaginative, an artist and one who “can change history”, and yet is uncertain to tale responsibility for the illegitimate child he brings in the world. On the other hand, Bill Gates is illustrated as the typical computer nerd, who leaves a Harvard education to start Microsoft with his friend Paul Allen. He is shown as driven, an opportunist who will stop at nothing to get the idea out there “first”.

2nd CASE STUDY in ACCOUNTING

Discuss the two forms of trial balance. give their cons and pros of each forms.

--The two forms of trial balance are trial balance of balances and trial balance of totals. The trial balance of balances is the listing of the debit and credit balances of each account in the general ledger that are remaining open after footing has been done. On the other hand, trial balance of totals is the listing of both debit and credit entries of the general ledger will appear in the listing including the closed account. For example, if the debit Notes Receivable account is P5,000.00 and the credit entry is also P5,000.00, under the trial balance of balances, the account will no longer appear as the account is close whereas under the trial balance of totals both total debit and credit of P5,000.00 each will be included.


The pros of the two forms are the following:


1. It ensures that the transactions recorded in the books of accounts have identical debit and credit amount.

2. Balance of each ledger account has been computed correctly.

3. Balance of each and every ledger account has been transferred accurately and on the correct side of the sheet on which trial balance has been prepared.

4. The debit and the credit columns of trial balance have been added up correctly.

5. Preparation of final accounts is not possible without preparing trial balance first.

6. Agreed trial balance is a prima facie evidence of the arithmetical accuracy of the accounting books maintained.

7. Errors which are revealed by preparing trial balance (listed below) are rectified even before the preparation of final accounts.

The only con of using a trial balance is the fact that it does not give accurate picture on real time basis since outdated valued of assets are used.

1.    What is posting? In what books of accounts this is being done? 

    --Posting is the process of transferring entries from the journal to the Ledger and it is the second step of the accounting process.To post is to summarize all journal entries and transfer them to the general ledger accounts. Posting is done at the end of an accounting period (monthly).
    --Posting is done in the GENERAL LEDGER.

2.    What is “cross-referencing” or “cross-indexing”? Explain its importance.
    --Cross-referring or cross indexing is the process wherein the folio column of the ledger contains the page number of the journal and simultaneously the folio column of the journal contain the page number or account number of the ledger.
    --It is for convenience purposes in using the folio and is easy to locate the account in general ledger.

3.    What is Footing? How is it accomplished in the General Ledger?
    --Footing is the process of adding each of the two amount columns of an account or item in the general ledger and finding their balances thereof.
    --In Footing the account, a well sharpened pencil should be used in writing the total of the amount and the account balance. If an account is debit balance (debit total is bigger than the credit total), the amount of difference is placed on the particular column of the debit side. If the account, on the other hand is credit balance (credit total is bigger than the debit total), the amount of difference is placed in the particular column of the credit side. If there is only one entry in any side of an account in the ledger, no footing is done and the entry is left as is. Footing is nearly the total of the column and if error is committed, it maybe erased and corrected easily because pencil is being used. Footing is not considered an entry posted in the general ledger.

4.    What is a Trial Balance?
   --Trial Balance is a list of all the nominal ledger (general ledger) accounts contained in the ledger of a business. This list will contain the name of the nominal ledger account and the value of that nominal ledger account. If the journal entries are error-free and were posted properly to the general ledger, the total of all of the debit balances should equal the total of all of the credit balances. If the debits do not equal the credits, then an error has occurred somewhere in the process. The total of the accounts on the debit and credit side is referred to as the trial balance.

5.    What is the source of a Trial Balance?
   --The sources of trial balance are the debit and credit entries of each account in the general ledger.

6.    What is the purpose of a Trial Balance?
  --The purpose of preparing a trial balance is to check the arithmetical or mathematical accuracy in posting and footing of the debit and credit entries of accounts in the General Ledger.

7.    When is a Trial Balance prepared?
  --The period covered by a trial balance depends upon the need of the bookkeepers or accountants to prepare this summary report. It can be on a monthly, quarterly, semi-annually or annually. This report can be prepared in any given period regardless of whether financial statements are prepared or not.


8.    When a Trial Balance is said to be “forced balance”?
  --The Trial Balance is said to be "forced balance" when a deliberate or an intentional act is done by letting it appear that the trial balance is in-balance although it is actually out of balance by changing the amount or changing an account with the amount of the unlocated difference, the trial balance is said to be forced balance which is never permissible in the accounting practice.

9.    Enumerate some of the errors committed that will make a trial balance to be ”out of balance”?
  --Some errors and omissions committed that will result a trial balance to be “out of balance” are as follows:   

• The footing of the debit and credit columns of the trial balance is wrong;(error)   
• An account with open balance in the General Ledger was not listed in the trial balance;(omission) 
• The footing of the account balance in the General Ledger is wrong;(error) 
• Posting the amount of an item to the wrong side of the account or ledger;(error) 
• Omission is posting of either debit or credit entry in the journal;(omission)

    The balance of an account is listed in the trial balance with a wrong amount, such as transposition of the amount or sliding of the amount of listing a different amount from the correct one.

10.    What are the possible errors that when committed, the trial balance will still be “in balance”?
     The following are errors that when committed, the trial balance will still be "in balance":

•  A Transaction may not have been recorded on the journal;(omission) 
• A journal entry may not have been posted in the ledger in its entirety;(omission) 
• Posting a correct amount to a wrong account;(error) 
• Wrong charging of account title in the journal entry and was carried to posting in the ledger;(error)

11.    Differentiate a “sliding error” from that of a “transposition error”.
   --In sliding error is committed when the decimal point was misplaced or slide while in the transposition error, the orders of the figures  was reversed. Example, in sliding error, 35 is incorrectly written as 3.5 while in transposition error 35 is incorrectly written as 53.

12.    Are omissions considered errors? Explain.
   --No, because omission refers to a mistake in a trial balance where it must be removed while errors refer to the mistake that can be corrected.

13.    Differentiate “single ruling” from “double ruling”?
   --Single ruling is done after listing the last account title while double rule is done when the trial balance is already in balance. Single rule is the line drawn across the two amount columns while double rule is the line drawn under the totals of both debit and credit columns.

14.    How are the accounts in the trial balance arranged?
-- The order of accounts is generally as follows:
•    Assets
•    Liabilities
•    Equity
•    Income
•    Expenses
No indention are made in listing the account titles and no peso sign for the amount.. Each account title must be alphabetically arranged.

CASE STUDIES

Case A

 
a)    What was he trying to do with the trial balance?
       He’s trying to make the trial balance appeared to be “in balance”.

b)    Do you think this error will be discovered? How? When? And who?
      The error committed by the bookkeeper will surely be discovered. This fault will be discovered when the general ledger, general journal, journal entries and the T-account will be checked and reviewed by the accountant and the auditors. In short, this deliberate act can be discovered during the audit or examination of books of accounts.

Case B
a)    Was the arrangement of the account correct?
      The arrangement of account made is definitely incorrect. The accounts must be arranged according by assets, liabilities, owner’s equity, income, expenses respectively.

b)    Do you agree when a trial balance is “in-balance”, the work is presumably correct?
       Yes, I do agree that when a trial balance is “in-balance” the work is presumably correct. Because we can take an assumption that no error has been committed in the process of journalizing and posting and we can say that there is accuracy in establishing the trial balance.
 

Case C
    Two students are discussing the use of a trial balance. They wonder whether the following errors, each considered separately would prevent the trial balance from balancing.
a)    The bookkeeper debited cash for P700,000 and credited salaries expense of P700 for payment of salaries.
b)    Cash collected on account was debited on cash account for P500 and service income was credited for P50.

What would you tell them? 

 
    I will tell the two students that the errors they present will absolutely prevent the trial balance from balancing because it will create an error when it comes to addition or subtraction of amount in the transactions. The error that they commit is a sliding error where in the decimal point was misplaced. The 700,000 was incorrectly written as 700 and the 500 was incorrectly written as 50.
    For example, in situation A, the amount of debit total is 800,000 and 700,000 of that total come from the debited cash. Since the written credited salaries expense is 700, the amount that appears in the credit total is probably 100,700. Therefore, the trial balance is out of balance because of the sliding error.

---

1st CASE STUDY in ACCOUNTING

1. Explain the nature of accounting system.

- An accounting system is a process whereby a specific output is produced by a given input. In an information accounting system, data is processed to provide information. Data is a collection of unprocessed facts, while information is data or facts that have been processed into a meaningful form.

In the normal course of events, a business undertaking will enter into a large variety of transactions. The details of a particular transaction are referred to as transaction data. The term transaction data therefore refers to the facts that completely describe a specific transaction.

The aim of an accounting system is to record the transaction data and then to process this data to provide information that is ultimately collected in the financial and management reports of the enterprise. There are two stages in the development of an accounting system, namely systems analysis and system design.

A good accounting system must comply with at least the following fundamental requirements. The system must provide decision makers with timely and accurate information relevant to the responsibilities and requirements; the internal control measures must be adequate to ensure the protection of assets and the provision of reliable information and the system must be sufficiently flexible to accommodate changes in the volume of activities and in the operating procedures without requiring drastic modifications.

2. Differentiate the account from T-account.

-       Account is the basic summary device of accounting. A separate account is maintained for each element that appears in the balance sheet and in the income statement. Thus, an account maybe defines as a detailed record of the increases, decreases and balance of each element that appears in the entity’s financial statements. The simplest from of account is known as the T-ACCOUNT because of its similarity to the letter “T”. T-account has three parts, the account title, debit side and the credit side.

3. State the basic rules of debit and credit.

-       The rule of debit and credit for income and expense accounts are based on the relationship of those accounts to owner’s equity. Income increases owner’s equity while expense decreases owner’s equity. Hence, increases in income are recorded as credits and decreases as debits. Increases in expenses are recorded as debits and decreases as credits.

4. What is the importance of double entity accounting?

-  The double entity provides a formal system of classification and recording business transactions. It recognizes the two fold effects of a transaction; the value received and the value parted with. This justified the equality of credit and debit amount. A debit side entry must have a corresponding credit side entry. Each transaction affects at least two accounts. The total debits for a transaction must always equal the total credits.

5. Discuss the role of accounting records.

-       Accounting records refers to all of the documents and books involved in the preparation of financial statement, records relevant to audit and financial reviews. This accounting records include records of assets and liabilities, monetary transactions, ledgers, journals and any supporting documents such as checks and invoices that are used by accountants in pursuing the primary objective of accounting which is communication through the financial statement. 

---

2nd case study in DATABASE

1. Definition of relational database.

            In 1970, relational database was invented by E. F. Codd at IBM. It consist of a collection of tables that store particular set of data for which the data can be accessed, processed, manipulated in many different ways without having to reorganize the database tables. The process by which data is organized logically is called normalization. Normalization regulates data’s structure and simplifies the way data is defined. The stored data is manipulated using a programming language called Structured Query Language (SQL).

            The primary unit of storage in a relational database is the relation (a two-dimensional table). The relational database can contain one or more of these relations, with each table consisting of a unique set of rows and columns. Each row contains a unique instance of data or single record for the categories defined by the columns. This column consist the attributes of the data or called fields. This unique instance of data is identified by the primary key. Primary key can be used to reduce redundancy of the stored data. For example, a typical business order entry database will include a table that describe a customer with columns for name, address, phone number, and so forth. Another table will describe an order: product, customer, date, and so forth. A user of the database could obtain a view of the database that fitted the user’s need. For example, a branch office manager might like a view or report on all customers that had bought products after a certain date. A financial service manager in the same company could obtain a report on accounts that needed to be paid from the same table.

            Most of database system in use today is based on the relational system. It is considered as powerful because it requires few assumptions about how the data is related or how it will be extracted from the database. As a result, the same database can be viewed in many different ways. The most important feature of relational systems is that a single database can be spread across several relations.

            There are four types of relationship in a relational database, namely: one-to-one, one-to-many, many-to-one and many-to-many relationship. In one-to-one relationship, one record in a table is related to another record in a separated table. In one-to-many relationship, one record in a table is related in multiple records in another table. For many-to-one relationship, more than one record in a single relates to only one record in another table. The many-to-many relationship refers to more than one record in a table relates to more than one record in another table.

            Relational database is used to match data by using common characteristics found within the data set. This grouping of data can help user to easily access and manipulate data, data can be monitored without difficulty, data redundancy can b e reduced and data inconsistency can be avoided. For example, a data set containing all the cake order transaction in a bakeshop can be grouped according by the date the transaction occurred, buyer’s name and so on. 

It is a database which stores and manages the information in tables, which are composed of rows and columns. The name 'Relational' came from that fact that the tables in such a database are nothing but a collection of similar type of information stored in form of rows. This is the reason why a table is also referred to as a relation in such a database.

2. Importance of Relational Database.

The relational model is the basis for any relational database management system (RDBMS). A relational model has three core components: a collection of objects or relations, operators that act on the objects or relations, and data integrity methods. In other words, relational database has a place to store the data, a way to create and retrieve the data, and a way to make sure that the data is logically consistent.

Usually, only one data type can be stored in a database table column. Columns in a database table have a fixed value. Single rows of a database table are uniquely identified by a unique value (typically a primary key). Multiple users can access a database table at the same time, with various combinations of read and write capabilities in different parts of the database. A database usually has transaction-control capabilities, making it possible to “roll back” a change if something happened to prevent it from completing successfully (such as a power failure). There are many tools for repairing and recovering databases.

In addition to being relatively easy to create and access, a relational database has the important advantage of being easy to extend. After the original database creation, a new data category can be added without requiring that all existing applications be modified.

The following are also the importance of relational database:

·         Data entry, updates and deletions will be efficient.

·         Data retrieval, summarization and reporting will also be efficient.

·         Since the database follows a well-formulated model, it behaves predictably.

·         Since much of the information is stored in the database rather than in the application, the database is somewhat self-documenting.

·         Changes to the database schema are easy to make.

3. What is the integrity rule (its definition)?

The relational model defines several integrity rules that are necessary part of any relational database. An integrity rule is used to promote the accuracy and reliability of stored data within the database and assures that data is consistent, certified and can be reconciled. In other words, there is a close correspondence between the facts stored in the database and the real world it models. These are the rules which a relational database follows in order to stay accurate and accessible. These rules govern which operations can be performed on the data and on the structure of the database.

4. What are the two types or general form of integrity rules?

There are two types of integrity rules: general and database-specific.

a.            General integrity rules

The relational model specifies two general integrity rules. They are referred to as general rules, because they apply to all databases. The two general integrity rules are the entity integrity and referential integrity. 

 - The entity integrity rule is very simple. It says that primary keys cannot contain null data. The reason for this rule should be obvious. Users can't uniquely identify or reference a row in a table, if the primary key of that table can be null. It's important to note that this rule applies to both simple and composite keys. For composite keys, none of the individual columns can be null. Fortunately, Microsoft Access automatically enforces the entity integrity rule for the users. No component of a primary key in Microsoft Access can be null.   
-   The referential integrity rule says that the database must not contain any unmatched foreign key values. This denotes that:

·   A row may not be added to a table with a foreign key unless the referenced value exists in the referenced table.

·   If the value in a table that's referenced by a foreign key is changed (or the entire row is deleted), the rows in the table with the foreign key must not be "orphaned."

In general, there are three options available when a referenced primary key value changes or a row is deleted. The options are:

·   Disallow. The change is completely disallowed.

·   Cascade. For updates, the change is cascaded to all dependent tables. For deletions, the rows in all dependent tables are deleted.

·   Nullify. For deletions, the dependent foreign key values are set to null.

b.                  Database-Specific Integrity Rules

All integrity constraints that do not fall under entity integrity or referential integrity are termed database-specific rules or business rules. These types of rules are specific to each database and come from the rules of the business being modeled by the database. It is important to note that the enforcement of business rules is as important as the enforcement of the general integrity rules.

Rules in Microsoft Access 2.0 are now enforced at the engine level, which means that forms, action queries and table imports can no longer ignore your rules. Because of this change, however, column rules can no longer reference other columns or use domain, aggregate, or user-defined functions.

Without the specification and enforcement of business rules, bad data will get in the database. The old saying, "garbage in, garbage out" applies pertinently to the of business rules.

 Business rules should be implemented to ensure that the data entered meets the requirements of a particular setting for the database. Business rules should be documented as they are implemented. This should detail each rule, where and how it is implemented and enforced within the database design. Over time these rules may change, and having each and every rule documented will make it much easier to find and modify the design.

5.      Discuss primary, candidate, alternate and foreign keys.

A key is an entity in a table that distinguishes one row of data from another. The key may be a single column, or it may consist of a group of columns that uniquely identifies a record.

Keys are crucial to a table structure for many reasons, some of which are identified below:

    

        - They ensure that each record in a table is precisely identified.
        - They help establish and enforce various types of integrity.
        - They serve to establish table relationships.

A.         PRIMARY KEY

·         A primary key will uniquely identify a row each record. It may or may not provide information about the record it identifies. It must not be Null-able that is if it exists in a record it cannot have the value Null. Primary key data should be immutable. This means that once set, the information should never be changed. Although it is possible to modify the information in a primary key column, it is inadvisable. This is because the change would need to be propagated to every linked table to maintain referential integrity. This usually prevents the use of data such as a car's registration number as the primary key; if a car's registration number is changed, the primary key information would need to be updated.

B.         CANDIDATE KEY

·   A candidate key is a superkey that has no unique subset; it contains no columns that are not 

necessary to make it unique. It is a column in a table which has the ability to become a primary 

key. It uniquely identifies the rows in a table. There can be more than 1 candidate key in a table,

 in which one should be a primary key.

·    A candidate key is one that can identify each row of a table uniquely. Generally a candidate 

key becomes the primary key of the table. If the table has more than one candidate key, one of 

them will become the primary key, and the rest are called alternate keys.

C.        ALTERNATE KEY

·       Any of the candidate keys that are not part of the primary key is called an alternate key. 

Alternate Key or Unique Key is similar to Primary Key, except it accepts null Values .So that

 the records can still be entered submitting null values to this attribute.

D.        FOREIGN KEY

·        A foreign key is an attribute or combination of attributes in a table whose values match

 a primary key in another table.

·        It is a referential constraint between two tables. It identifies a column or a set of columns in one (referencing) table that refers to a set of columns in another (referenced) table.  It is a reference to a key in another relation, meaning that the referencing table has, as one of its attributes, the values of a key in the referenced table. Foreign keys need not have unique values in the referencing relation. Foreign keys effectively use the values of attributes in the referenced relation to restrict the domain of one or more attributes in the referencing relation.

·        A foreign key could be described formally as: "For all tables in the referencing relation projected over the referencing attributes, there must exist a table in the referenced relation projected over those same attributes such that the values in each of the referencing attributes match the corresponding values in the referenced attributes."

---