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shabbir 25May2005 18:05

Database interview questions for beginner
 
1. Explain the difference between a database administrator and a data administrator.

Database Administrator :- A person (or group of people) responsible for the maintenance and performance of a database and responsible for the planning, implementation, configuration, and administration of relational database management systems.

Data Administrator :- The individual or organization responsible for the specification, acquisition, and maintenance of data management software and the design, validation, and security of files or databases. The DA is in charge of the data dictionary and data model.

2. Explain the difference between an explicit and an implicit lock.

Explicit Lock :- Lock is explicitly requested for a record or table.
Implicit Lock :- Lock is implied but is not acquired

3. What is lock granularity?

There are many locks available for the database system to have like
Intent Shared, Shared, Intent exclusive, exclusive and Shared Intent exclusive.
Locking granularity refers to the size and hence the number of locks used to ensure the consistency of a database during multiple concurrent updates.

4. In general, how should the boundaries of a transaction be defined?

A transaction ensures that one or more operations execute as an atomic unit of work. If one of the operations within a transaction fails, then all of them are rolled-back so that the application is returned to its prior state. The boundaries that define a group of operations done within a single transaction.

5. Explain the meaning of the expression ACID transaction.

ACID means Atomic, Consistency, Isolation, Durability, so when any transaction happen it should be Atomic that is it should either be complete or fully incomplete. There should not be anything like Semi complete. The Database State should remain consistent after the completion of the transaction. If there are more than one Transaction then the transaction should be scheduled in such a fashion that they remain in Isolation of one another.Durability means that Once a transaction commits, its effects will persist even if there are system failures.

6. Explain the necessity of defining processing rights and responsibilities. How are such responsibilities enforced?

One of the reason to define rights is the security in the database system. If any user is allowed to define the data or alter the data then the database would just be of no use and so processing rights and responsibilities are clearly defined in any database system. The resposibilities are enforced using the table space provided by the database system.

7. Describe the advantages and disadvantages of DBMS-provided and application-provided security.

DBMS provided security :- Any database system requires you to login and then process the data depending on the rights given by the DBA to the user who has logged in. The advatage of such a system is securing the data and providing the user and the DBA the secured platform. Any user who logs in cannot do whatever he want but his role can be defined very easily. There is no major disadvantage about the DBMS provided security apart from overhead of storing the rights and priviledges about the users.

Application-provided security :- It is much similar to the DBMS provided security but the only difference is that its the duty of the programmer creating the application to provide all the seurities so that the data is not mishandled.

8. Explain how a database could be recovered via reprocessing. Why is this generally not feasible?

If we reprocess the transaction then the database can be made to come to a state where the database is consistent and so reprocessing the log can recover the database. Reprocessing is not very feasible for a very simple reason that its very costly from time point of view and requires lots of rework and many transaction are even rollback giving more and more rework.

9. Define rollback and roll forward.

Rollback :- Undoing the changes made by a transaction before it commits or to cancel any changes to a database made during the current transaction
RollForward :- Re-doing the changes made by a transaction after it commits or to overwrite the chnaged calue again to ensure consistency

10. Why is it important to write to the log before changing the database values?

The most important objective to write the log before the database is changed is if there is any need to rollback or rollforward any transaction then if the log are not present then the rollback rollforward cannot be done accurately.

rollings 13Sep2007 14:55

Re: Database interview questions for beginner
 
Thanks shabbir. , just got What I wanted

shabbir 13Sep2007 17:21

Re: Database interview questions for beginner
 
My pleasure.

clocking 30Sep2007 08:27

Re: Database interview questions for beginner
 
Hi shabbir, I hesitate to suggest you this problem.
Can You support me to designing a database for images of data?

stylishkishore 26Jul2009 20:18

Re: Database interview questions for beginner
 
nice ...very nice.

naimish 20Aug2009 16:07

Re: Database interview questions for beginner
 
Wouldn't know we can also post like this :D Thanks.

Daisy 10Dec2009 12:53

Re: Database interview questions for beginner
 
Quote:

Originally Posted by rollings (Post 17832)
Thanks shabbir. , just got What I wanted

it was really benefit for me. because i am prepairing for competitative exams. thanks a lot shabbir

sameer_havakajoka 10Dec2009 13:04

Re: Database interview questions for beginner
 
can we plz hav sum sql server questions and answers too?

jerryvn01 30Jun2010 13:31

Re: Database interview questions for beginner
 
Hi,

Thanks very much for this comment. It help me to think about my ideals.

Tks again and pls keep posting.

ksrao 31Aug2010 10:03

Re: Database interview questions for beginner
 
Hi,

This is really a useful set of oracle sql interview questions for beginner.
I found some more good questions for free at wiziq .


Kolla Sanjeeva Rao.
OCP
Oracle.

Malik-Qasim 26Sep2010 15:09

Re: Database interview questions for beginner
 
very nyc

GoodCoder 15Feb2011 11:56

Re: Database interview questions for beginner
 
Hi,

It is really helpful. :)

Thanks.

vinaykumar4670 13Apr2011 17:54

Re: Database interview questions for beginner
 
thanks for support me.

patricholier 21Apr2011 20:20

Re: Database interview questions for beginner
 
Hi

This topic help me a lot in developing my project. I will contribute more when I finished it.

Eldridge13 23May2011 07:04

Re: Database interview questions for beginner
 
Hi, shabbir
This topic is very useful for me. It makes me think about my ideals.

shabbir 23May2011 10:06

Re: Database interview questions for beginner
 
Quote:

Originally Posted by Eldridge13 (Post 83325)
Hi, shabbir
This topic is very useful for me. It makes me think about my ideals.

Great to see that.

hamburg113 19Aug2011 07:17

Re: Database interview questions for beginner
 
Hi

I found that a member asked same question in this forum some months ago.

Pls use search box to find this questions with comments

shabbir 19Aug2011 08:30

Re: Database interview questions for beginner
 
Quote:

Originally Posted by hamburg113 (Post 86173)
Hi

I found that a member asked same question in this forum some months ago.

Pls use search box to find this questions with comments

Why don't you yourself use the same search box and find that user's query and reply to it instead of adding your reply here.

angel46 22Aug2011 12:06

Re: Database interview questions for beginner
 
i have a question..
Q)find the no. of superkeys that can be formed in the relation R(a1,a1,..,an) having a1 and a2 as keys?

jhonackerman 19Oct2011 11:27

Re: Database interview questions for beginner
 
Hey thanks for the answering these interview questions,i really appreciate it.

neerjasoftwares 19Oct2011 12:13

Re: Database interview questions for beginner
 
hello sir, its being a rich experience to be here......................................SIr give us some more questions that are being commonly asked in an Interview when you are a fresher.
neerja softwares.com

bobwarner01 19Oct2011 12:15

Re: Database interview questions for beginner
 
Thanks for sharing info.That really so nice to hear about it. My site faced this same kinda problem but at that point I was no aware what really happened ! Now all clear

bobwarner01 19Oct2011 12:16

Re: Database interview questions for beginner
 
Thanks for sharing info.That really so nice to hear about it. I faced this same kinda problem but at that point I was no aware what really happened ! Now all clear.

hambim336 30Dec2011 18:41

Re: Database interview questions for beginner
 
Hi,

Good ideal, pls try to keep posting. I like this topic very much and I will digged this one. Tks again.

thu062012 14Feb2012 19:26

Re: Database interview questions for beginner
 
Hi,

Thanks very much for this comment. It help me to think about my ideals.

Tks again and pls keep posting.

hua052011 9May2012 10:08

Re: Database interview questions for beginner
 
Hi

I found that a member asked same question in this forum some months ago.

Pls use search box to find this questions with comments

aroraaisha 19Jul2012 17:15

Re: Database interview questions for beginner
 
Thanks for your valuable post.


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