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Wednesday, 4 September 2013

DBMS : few questions for freshers

Hello , once you are ready with the 'HR' type of questions , (you can take a look at some of the questions and answers at HR questions)  it is obviously important for getting ready for the technical and one of the subjects ,  and DBMS is one of the leading ones from both the parties. So I pen down few DBMS questions, this are all indicative ones , just to give you an idea on the depth and breadth. Normalization, Transactions , SQL and Indexing ,  I have seen to be all time favorites.

Feel free to give your comments , post answers , more questions , any other feedback.

Imagining you guyz are reading this because of your impending campus , read smartly , fine balancing with enjoying life , work on a plan and you will be partying in time :)

DBMS :
General


  1.    What is OLAP and OLTP?
  2.    What are the advantages of DBMS over file system? ( Do not forget key ones like transaction , normalization,  indexing , locking , logging etc. )
  3.     Why RDBMS called RDBMS ? Stress on the relational part.
  4.     Draw an ER Diagram for the project you did ? 
  5.    .What is the degree of a relationship? Does relationships always needs a table ?
  6.      How do you achieve generalization and specialization in an ER?

Normalization

  1.      Why do we normalize?
  2.      What are the different anomalies?
  3.      Why do we denormalize ?
  4.      Give an example of a table , which is not in 3 NF , explain diffrent anomalies in that context ,  tell how you will make it normalized



Transaction

  1. What is a transaction?
  2. What is ACID property? Explain each one with example.
  3. How the durability property is implemented ?
  4. How do you implement a transaction from a programming language like C# or java?
  5.  Can a transaction be partially committed ?
  6. What is locking , what is two phase locking ?
  7. What is seralizability ? 

Integrity 


  1. What are different type of constraints ?
  2. What is primary key , foreign key , candidate key ?
  3. What is unique , Check constrains 
  4. Difference between a primary key and unique constraint ?
  5. Is it possible to create a table with out a primary key ?
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Indexing:

  1.  Why do we use index?
  2. What are the overheads of index?
  3. What is the difference between clustered index and a non-clustered index ?
  4.  What is the difference between B Tree and B+ Tree
  5.  Another way of asking the same question , what are the diffrent data structures that are used 

SQL:
  1.  What is difference between a function and stored procedure ?
  2.  What is cursor ?  What are the different types of cursor in oracle ?
  3. What are the different indices that oracle support?’ ( Special focus on bitmap indices)
  4. What is the difference on where and having clause ? 
  5. Questions on NULL
  6. What is the difference between char data type and varchar data type?
  7. What is a view?  What is materialised view?  Why they are used?What are different types of joins , what is difference between a Cartesian product and a full outer join ( Practise this with few examples )
  8. What is the function of UNION ?  Is it different from UNION ALL? 
  9.  What is DDL and DML,  how truncate is different from Delete
  10. Where will you use trigger , what are the different types of trigger ?
  11. Why do we create packages ?
  12. How do we handle exceptions?
  13. What is the role of dual ?
  14. If two tables have PK - FK relationship and you want when the PK gets deleted , the FK entries also gets deleted , how do you do that ?
  15. Why and how do you create sequences?
  16. How can you delete dupicate data from a table ?
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