Friday, November 21, 2014

DBMS Transaction Management - ACID Properties

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In this tutorial we will learn about how transaction is done in database management system, ACID Properties and States of Transactions.

DBMS Transaction Management - ACID Properties

Transaction Management
What is Transaction Management?

Transaction is group of task; sometimes even single task is called transaction. To understand transaction, let we take one example of money transfer.
For example, there are two friends named Niraj and dhimant. Niraj goes to study out of station. One fine day he needs money for to buy books. He called dhimant and asked for money. Dhimant agrees to transfer money to niraj (as bank transfer is fastest way to money transfer as of now). Dhimant ask for niraj’s bank account.Dhimant use online money transfer via login to online bank account. Transfer Rs.1000 to niraj. Niraj confirms that he received the amount and thanks dhimant.

In above transaction, there are multiple transaction has took place. Like, 1st dhimant login to his online bank account, 2nd before transfer bank check his available balance, 3rd after confirming his bank balance, bank transfer Rs.1000 to niraj’s account, 4th bank shows new balance to dhiamant after transfer and final taks, closing online bank account.

So, A simple transaction of moving an amount of 100 from dhimant to niraj involves many low level tasks.

ACID Properties (Atomicity, Consistency, Durability, and Isolation)

As we discussed that transaction includes lots of low level tasks and as you know transaction is very small amount of program (i.e transfer of amount). To maintain accuracy of transaction, database maintains some properties for completeness and data integrity.  These properties is called ACID Properties, A for Atomicity, C for Consistency, I for Isolation, and D for Durability.

1. Atomicity: - As we know transaction has several low level operations but as per atomicity property, transaction is atomic unit. Which means either all operation should be executed or none. In other words, there is not state in database where transaction is left partially completed. So, only two states, either before the execution of the transaction or after the execution.

2. Consistency: - Consistency property states that after transaction is finished, database remain in consistent state. No data should be affected by execution of transaction. If DB was in consistent state before execution of transaction /process, it must be remain in consistent state after execution.

3. Durability: - As per durability state, if all updates made on Database will persist even if system fails and restart. If some user updates data in database and is not written on database because of system failure or any other reason, than data will be updated once system is up.

4. Isolation: - As you know database used to execute more than one transactions simultaneously and in parallel. As per isolation property, no transaction should be affect existence of other transaction. All transaction should be executed. 

Read about Overview of E-R Diagram.
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E-R Diagram Overview - DBMS

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In this tutorial we will learn about E-R Diagram, Components of E-R Diagram, and much more about E-R Diagrams.

E-R Diagram Overview  & Components of E-R Diagram

E-R Diagram Overview
Entity relationship model defines the conceptual view of database. It works around real world entity and association among them. At view level, ER model is considered well for designing databases.

In other words, E-R diagram is nothing but visual representation of how data is related with each other. To understand relationship between data, we use E-R Diagrams.

Below is list of symbols and notations (components of E-R Diagram) used in E-R Diagram.

1. Entity: - Entity is object, place, person, class, it is real world entity. We use rectangles to show entity. For example employee, manager, department are entity of organization.

a. Weak Entity: - If one entity is dependent on another entity, it is called weak entity. This entity dose not has their own key attributes. Double rectangle is used for weak entity.

2. Attributes:- Things which represented using their properties are called attributes. Attributes must have values. For example, student has attributes like name, course, age etc.

An attribute is represented using eclipse.

a. Key attribute: - Key attributes is nothing but the main characteristics of an entity. This is used for primary key. We use ellipse with underlines for key attribute.

b. Composite Attribute: - If one attribute have their own attribute than it is called composite attribute. (i.e address has zip code, city, state).
       
3. Relationship: - A relationship (as name describe) represent relation between two entities. We use diamonds to represent relationship.

a. Binary Relationship: - Binary relationship is relation between two entities.

i. One to one Relationship:- One student can enroll in one course at a time.
ii. One too many relationship: - One course have many students.
iii. Many too many: - Many students has enrolled in many course.

b. Recursive relationship: - When one entity is related to itself is known as recursive relationship. For example, Manager who is employee manage other employee.

c. Ternary Relationship: - Relationship of degree three is called ternary relationship.

Now read about Normalization of Database.
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Thursday, November 20, 2014

Normalization of DATABASE

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In this tutorial, we will learn about Normalization of database, why we need normalization of database, objective of normalization of database, normalization rules (1nf, 2nf,3nf, and BCNF) in detail.

Normalization of DATABASE

Normalization of DATABASE
What is normalization of database?

It is a technique of organizing data in database. Database normalization is the process of organizing the fields and tables of a relational database to minimize redundancy. In other words, normalization involves breaking big tables in smaller one by defining relationship between small tables and big tables.

There are mainly two objective of using normalization;

1.    To reduce redundancy.
2.    To ensure data is logically stored.

What are the normalization rules? (Relational Model)

1.    First normal form
2.    Second normal form
3.    Third normal form
4.    BCNF (Boyce and codd normal form)

1. First Normal Form (1NF)

In the first normal form, Two rows cannot have duplicate values. In other words, each column must have unique values. To achieve uniqueness, Primary Key is used. Primary key is usually single column. For example, in a student table of aspirants who applied for IBPS Exams. Then one student, ramesh can also apply for IBPS PO, IBPS SO and IBPS Clerk. So, to reduce redundancy, we will store ramesh’s data in three different rows.

But the problem with first normal form is, it itself increase redundancy as we will have more columns instead of single row data. But 1NF will give unique data.

2. Second Normal Form (2ND)

In second normal form, we will use candidate key to reduce partial dependency with primary key. Which means if any of the columns has same value with primary key column; it will fail to be in 2nd normal form.
For example, if we have to add ramesh age in above example, then we will have one more column and we have more duplicate data, and it will create more problems to fetch data from table. So, what we do is create another table in which we will have student’s information along with age only. And separate table for students and the exam name.

3. Third Normal Form (3NF)

In Third normal form, it applies on every non-prime attribute of table must be dependent on primary key. Which means transitive functional dependency should be removed form table. (i.e A depends on B, B depends on C, C depends on A, A>B>C>A).

For example, If we have to store address of students who appeared in IBPS Exam (Continue with above example) than we will add street, city, state, zip code columns. But street name, city, states are depends on zip code only. So to remove this transitive functional dependency, we will create separate table for address of students.

So, third normal form gives advantage like we have low amount of duplicate data, and we maintained data integrity.

4. BCNF (Boyce and codd normal form)

It is higher form of third normal form, which deals with tables which cannot be handled by third normal form. Table which does not have multiple overlapping candidate key is said to be BCNF.
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IBPS PO/MT IV 2014 Result Declared - Active Link

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Are you appeared on IBPS PO CWE 2014? If yes than its a good news for you people, IBPS has announced the exam result of IBPS PO/MT IV 2014. The IBPS PO exam which was taken last month's exam result is now accessible. Check out the below mentioned link to check your ibps po exam result.

IBPS PO/MT IV 2014 result

Click here to check your IBPS PO 2014 Exam result.

Just visit on above link, enter your roll no or registration no along with your password or date of birth to check your ibps po result.

First of all congratulations for all the candidate who cleared IBPS PO IV online test. And the people who failed, don't worry try again, you will make it soon. you can appear for SBI Clerk exam (which is going to held in January month).

Also you can apply for IBPS SO 2014 Exam now, which is recruitment exam for recruiting scale 1 officer as specialist officer in IBPS banks. If you need any study material for upcoming IBPS Exams, you can keep visiting us for more study material here.

IBPS PO Interview Dates for IBPS PO CWE IV Pass out candidates

IBPS PO interview process on 23rd November 2014 (Sunday). for more updates, keep visiting us.

We are here providing all study material, current affairs and other bank exam related information on daily basis. you can keep visiting us for more updates on ibps bank exam or sbi bank exam. For more updates, you can also join us on facebook too.

By the way, Did you cleared exam or not? Let us know in comment below. Thank you.
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Current Affairs of 20th November, 2014

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Check the important current affairs and daily general knowledge update of 20th November, 2014 from politics, business, economics, sports and all other areas.

Current Affairs of 20th November, 2014

20th November, 2014
1. 2014’s indira Gandhi prize for peace, disarmament and development is given to ISRO (India space research organization).  ISRO has been chosen for their contribution towards strengthen international cooperation in peaceful use of space.
 

2. In 2G spectrum case, honorable Supreme Court of india has removed Director of CBI Ranjit sinha from investigation, saying that he helped some accused and tried to influence probe.
 

3. 5th International film festival of india had begun today in goa. Information and broadcasting minister Shri Arun Jeitely has inaugurated IIFI festival 2014.Arun jeitley and shri amitabh bachchan (who was chief guest of IIFI) has confer Superstar Rajnikant centenary  award for Indian film personality of the year. Total 178 films from 78 countries to be screened in IIFI 2014.
 

4. After Prime minister narendra modi’s “Make in india” champaign to increase investment in india, HRD ministry is going to introduce “Think In India” champaign to encourage students and research fellows to come up with new idea to keep the talent in india from leaving abroad.

5. Union cabinet cleared 3 framework agreements with SAARC countries to enhance rail and road connectivity and setting up regional power grid. Also, an MOU also signed between India and Nepal to promote tourism. Narendra modi to visit Nepal on 25th November, 2015.
 

6. Kotak Mahindra bank to acquire all shares of  ING Vysya Bank to increase market position. Kotak Mahindra bank has informed BSE after market hours.
 

7. Assam Zoo (of guwahati) set to become the first zoo in world to have the critically endangered Pygmy Hog(Porcula salvania).
 

8. As per OECD (Organization for economic co-operation and development), India is coming out of economic slowdown of 25 years. OECD has predicted India’s growth rate for 2015-16 is 6.6% which was 5.7% in may, 2014.
 

9. Maharashtra government has cleared two more metro projects (1 from dahisar to mankhurd and 2nd wadala to kasarvadavali in Mumbai). Both projects to cost Rs.25,605 cr and Rs.19,097 cr respectively. These both projects was approved in a MMRDA board meeting which was chaired by Chief minister devendra fadnavis.
 

10. Indian shuttlers Sania nehwal and K srikanth enters in quarter-final of singles game in hong kong super series of badminton tournament. It is mentioned that they recently won china open badminton 2014 tournament.
 

11. ICC ODI Ranking update :- Team India again on Top place, while Virat kohli is on 2nd spot of batting chart.
 

And In international affairs…
 

12.Sri lanka president Mahindra rajapaksa has declared snap presidential election to seek record third term.
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Syllabus for IBPS Specialist Officer exam 2014

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Are you appearing for the IBPS specialist officer examination this year? You must be wondering about the syllabus for the exam! Right? Well, you have come up to right place. Here, I have included the complete syllabus. Let’s have a look at it.

Syllabus for IBPS Specialist Officer exam 2014

Institute of Banking Personnel Selection (IBPS) has announced the recruitment for the post of specialist officers. This is the best opportunity for the candidates who are looking for the good job in banking sector. Well, there will be 22 banks participating in this examination. Isn’t it great? Are you ready for the examination? Do you know what the syllabus for IBPS specialist officer exam 2014 is? I have explained everything in detail below.

Syllabus for IBPS specialist officer exam 2014:

Syllabus for IBPS specialist officer exam 2014

First of all, there are sections including,

-    English Language
-    Reasoning
-    Quantitative Aptitude
-    General Knowledge/Banking Awareness
-    Professional Knowledge

These are the sections of syllabus for IBPS specialist officer exam 2014. What are you waiting for friends? Just get the best books for IBPS specialist officer exam 2014 and start your preparation in advance.

The IBPS conducts examination every year successfully and this year also there will be great number of candidates will appear. Are you one of them? If yes then you must have a look at our article for “Study Tips to crack IBPS specialist officer exam”.

What to do?

Why waste time friends? Make your own time table and make a proper schedule for reading. Moreover, you can solve previous year’s question papers to get the idea about exam paper pattern as well as type of questions to be asked in the examination. You can also mark important topics to be focused for exam. In addition, also try to solve practice papers. It will help you to analyze your preparation level.

In case of any doubts or questions regarding syllabus or anything please leave comment below. Just prepare well and score good marks in exam. Moreover, get help of our other articles on IBPS specialist officer exam 2014.

We wish you all the very best for exam in advance!
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DATABASE MANAGEMENT SYSTEM - DBMS

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What is DATABASE MANAGEMENT SYSTEM - DBMS? below is overview of DATABASE MANAGEMENT SYSTEM - DBMS, advantage of DBMS, Types of DBMS.

Database management system is consist of 5 parts. 1st data, 2nd information, 3rd data processing,  4th meta data and 5th database. If we combine all three parts in one portion we can have a “database management system”.  So, to know about database management system, you need to look in to all these 5 parts.

DATABASE MANAGEMENT SYSTEM - DBMS

DATABASE MANAGEMENT SYSTEM
1. Data :- Data is nothing but the raw material, from which we can drive some useful information. So, data is called unorganized facts. Price, weight, some number of items will be called data.

2. Information :- If we process the data, in such a way that increase its value, to the person who use this data, is called information. In other words, information is processed data. There is very slight difference between data and information, So the main difference between data and information is data is unorganized facts while information is processed data.

3. Data processing :- So, the process of processing unorganized facts into meaningful information is called data processing.

4. Meta Data :- Meta data is nothing but data about data.So, meta data have information about other data. Meta data gives you answer about how and where the data is stored.

5. Database :- And last, Database is collection of information. If we store information about some organization, (i.e hospital) than it is called hospital’s database. Likewise, we can have collage’s database(will have information about each student), city database (will have information about city), facebook database (will have information about user of facebook) etc. These are the examples of database.

So, Now you must have understood the meaning of DATABASE MANAGEMENT SYSTEM.

Database management systems (DBMS) are computer software applications that interact with the user, other applications, and the database itself to capture and analyze data.

In other words, DBMS is software who manages collection of data.

Advantages of DBMS :- Why we use DBMS, why we need DBMS? Here is advantages of DBMS.

1. Data independence :- In database, you can store multiple files, folders and many more thing. Any one authorized user can edit particular file without affecting other file. DBMS provides efficient access to data.

2. Low Redundancies :- DBMS provide low redundancies (means no duplicate files). If you have already saved file with name ibps.jpg than DBMS will pop up message, The file named ibps.jpg is already exist, do you want to replace it?

3. Data integrity :- DBMS provide Data integrity which means the values entered in files are valid or not. For example, if you enter name in the filed of mobile number, it will create confusion, right.  So, DBMS will allow numeric values in mobile number filed, so no one can enter name (alphabet) values in mobile number filed.

4. Data security :- DBMS Secures your data with security software, provide authorization service, so only authorized user can access to your data.

5. Sharing :- DBMS Provides sharing of data between authorized users. For example, you and your brother can share and view information stored in your computer at the same time as well as different times.

6. Backup and recovery :- In case of data loss or virus attack, if you have taken back up of your data, you can recover it, and avoid data loss.

Types of Database :- What are the types of DATABASE?

The database may be of different types but there are two generic database architectures. These are:

1. Centralized Database :- A database which is stored in single computer and many user can access is called centralized database. There are 3 examples of centralized database.

a. Personal Computer database
b. Client/server database
c. Central Computer database.

2. Distributed Database :- A database which is located on multiple places is called distributed database. For example, many organization (i.e bank) has multiple branches and each branch have their own database, which is connected to central database. Below is example of Distributed Database.

a. Homogenous database
b. Heterogeneous database.

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