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SQL Server Interview Questions and Answers – Part 1

April 15, 2007 by pinaldave

SQL Server Interview Questions and Answers

Print Book Available (207 Pages) | Sample Chapters

UPDATE : Interview Questions and Answers are now updated with SQL Server 2008 Questions and its answers. New Location : SQL Server 2008 Interview Questions and Answers.

What is RDBMS?
Relational Data Base Management Systems (RDBMS) are database management systems that maintain data records and indices in tables. Relationships may be created and maintained across and among the data and tables. In a relational database, relationships between data items are expressed by means of tables. Interdependencies among these tables are expressed by data values rather than by pointers. This allows a high degree of data independence. An RDBMS has the capability to recombine the data items from different files, providing powerful tools for data usage.

What is normalization?
Database normalization is a data design and organization process applied to data structures based on rules that help build relational databases. In relational database design, the process of organizing data to minimize redundancy. Normalization usually involves dividing a database into two or more tables and defining relationships between the tables. The objective is to isolate data so that additions, deletions, and modifications of a field can be made in just one table and then propagated through the rest of the database via the defined relationships.

What are different normalization forms?

1NF: Eliminate Repeating Groups
Make a separate table for each set of related attributes, and give each table a primary key. Each field contains at most one value from its attribute domain.
2NF: Eliminate Redundant Data
If an attribute depends on only part of a multi-valued key, remove it to a separate table.
3NF: Eliminate Columns Not Dependent On Key
If attributes do not contribute to a description of the key, remove them to a separate table. All attributes must be directly dependent on the primary key
BCNF: Boyce-Codd Normal Form
If there are non-trivial dependencies between candidate key attributes, separate them out into distinct tables.
4NF: Isolate Independent Multiple Relationships
No table may contain two or more 1:n or n:m relationships that are not directly related.
5NF: Isolate Semantically Related Multiple Relationships
There may be practical constrains on information that justify separating logically related many-to-many relationships.
ONF: Optimal Normal Form
A model limited to only simple (elemental) facts, as expressed in Object Role Model notation.
DKNF: Domain-Key Normal Form
A model free from all modification anomalies.

Remember, these normalization guidelines are cumulative. For a database to be in 3NF, it must first fulfill all the criteria of a 2NF and 1NF database.

What is Stored Procedure?
A stored procedure is a named group of SQL statements that have been previously created and stored in the server database. Stored procedures accept input parameters so that a single procedure can be used over the network by several clients using different input data. And when the procedure is modified, all clients automatically get the new version. Stored procedures reduce network traffic and improve performance. Stored procedures can be used to help ensure the integrity of the database.
e.g. sp_helpdb, sp_renamedb, sp_depends etc.

What is Trigger?
A trigger is a SQL procedure that initiates an action when an event (INSERT, DELETE or UPDATE) occurs. Triggers are stored in and managed by the DBMS.Triggers are used to maintain the referential integrity of data by changing the data in a systematic fashion. A trigger cannot be called or executed; the DBMS automatically fires the trigger as a result of a data modification to the associated table. Triggers can be viewed as similar to stored procedures in that both consist of procedural logic that is stored at the database level. Stored procedures, however, are not event-drive and are not attached to a specific table as triggers are. Stored procedures are explicitly executed by invoking a CALL to the procedure while triggers are implicitly executed. In addition, triggers can also execute stored procedures.
Nested Trigger: A trigger can also contain INSERT, UPDATE and DELETE logic within itself, so when the trigger is fired because of data modification it can also cause another data modification, thereby firing another trigger. A trigger that contains data modification logic within itself is called a nested trigger.

What is View?
A simple view can be thought of as a subset of a table. It can be used for retrieving data, as well as updating or deleting rows. Rows updated or deleted in the view are updated or deleted in the table the view was created with. It should also be noted that as data in the original table changes, so does data in the view, as views are the way to look at part of the original table. The results of using a view are not permanently stored in the database. The data accessed through a view is actually constructed using standard T-SQL select command and can come from one to many different base tables or even other views.

What is Index?
An index is a physical structure containing pointers to the data. Indices are created in an existing table to locate rows more quickly and efficiently. It is possible to create an index on one or more columns of a table, and each index is given a name. The users cannot see the indexes, they are just used to speed up queries. Effective indexes are one of the best ways to improve performance in a database application. A table scan happens when there is no index available to help a query. In a table scan SQL Server examines every row in the table to satisfy the query results. Table scans are sometimes unavoidable, but on large tables, scans have a terrific impact on performance.

Clustered indexes define the physical sorting of a database table’s rows in the storage media. For this reason, each database table may have only one clustered index.
Non-clustered indexes are created outside of the database table and contain a sorted list of references to the table itself.

Reference : Pinal Dave (http://blog.SQLAuthority.com)

Posted in Pinal Dave, Software Development, SQL, SQL Authority, SQL Cursor, SQL Download, SQL Index, SQL Interview Questions and Answers, SQL Joins, SQL Performance, SQL Query, SQL Scripts, SQL Security, SQL Server, SQL Stored Procedure, SQL Tips and Tricks, SQL Trigger, T SQL, Technology | 75 Comments

75 Responses

on June 29, 2007 at 7:26 am Vijay

Its AWESOME , and your rocking with SQLSERVER. keep it up and try to increase the content and more readble.
on July 2, 2007 at 2:18 pm Jinu

Its really nice.This will help me to get a job.Please send some interview tips for sql sever2005 also.
Jinu
on July 8, 2007 at 3:50 am kumar

SIR,

it is really awesome. you are great. you are doing a good job for coming generation.

my salute for you.

thanking you & best regards

kumar
on July 13, 2007 at 3:56 am Rahul Saini

Exactly how many colums can add in any table?
on July 19, 2007 at 5:05 am Rakesh

Its good
on July 20, 2007 at 12:24 am kalaiarasan

very nice
on July 20, 2007 at 12:25 am kalaiarasan

it is really awesome. you are great. you are doing a good job for coming generation.

my salute for you.

thanking you & best regards
on July 23, 2007 at 9:28 pm Jawa

cool stuff
on July 27, 2007 at 2:14 am Praveen Barath

Appriciated !! but i guess all depends on level which you going for ,for beginners its really usefull !!

cheers
on July 27, 2007 at 7:30 am SQL SERVER - Data Warehousing Interview Questions and Answers - Part 2 Journey to SQL Authority with Pinal Dave

[...] Jul 27th, 2007 by pinaldave What are normalization forms? Please visit this article. [...]
on August 10, 2007 at 12:55 pm Ruby

Thank you so much………Appreciate the efforts you have taken to compile them all……..

Regards…
on August 14, 2007 at 2:29 am a.SENTHIL MURUGAN

hello sir

now your doing the better and good job …..its very nice for our future generation…pls update new type of questions……….
on August 17, 2007 at 12:25 pm Deepak

Amazing, Astonishing!!!! this is great help… truly appreciated.
on August 22, 2007 at 5:40 am MAHENDRA RANE

I READ TO QUESTION THAT IS AMAZING.
THIS IS GREAT HELP …….
TRULY APPRECIATED.

IT IS REALLY AWESOME YOUARE GREAT. YOU AREDOING A GOOD JOB FOR COMING GENERATION.

THINGING YOU & BEST REHARDS
on August 23, 2007 at 2:12 am Steve

Can we update the data of Base table through View?
on August 23, 2007 at 2:38 am sandeep

This is Good
on August 24, 2007 at 12:16 pm Sunny

Hey Steve,

You can modify the data through view.
There are a few things you should consider….. using instead of triggers or using updatable partitioned views.
If none of these are used then there are few thing you should consider……
one cannot use data modification statements on more than one underlying table in a single statement and also while updating one should make sure about the column restrictions (constraints, nullability…..)
Hope this helps you.
on August 29, 2007 at 8:29 pm Himanshu

Hi Pinal Dave,

How can i delete duplecate records from the table.

Himanshu
on August 30, 2007 at 3:00 am Aman

Hi Pinal Dave,

Plz suggest me what should i do for DBA course
on September 13, 2007 at 2:29 pm Shenouda Nageub

This a good reference.
on September 18, 2007 at 7:12 am tropic

See complete Maximum Capacity for SQL Server 2005 here:

http://msdn2.microsoft.com/en-us/library/ms143432.aspx
on September 26, 2007 at 1:12 am gyanendra

hi friend,
i m new for this site,and i feel that it is one of the best site for getting the information regarding the sql and other one for interview purpose and for knowledge enhancement.
on October 18, 2007 at 4:35 am vijay raju

hi

mr.dave

its really good.

try to put the details about the DTS and Linked Servers
concepts with examples. That will me more useful for all.

Thanking u for providing these Questions with Answers.

regards

vijay raju
on October 26, 2007 at 9:42 pm swapna

Dear sir,

My heartfull thanks to u,this is really good,your helping me more………….I Think this one is helpfull for everyone..

Thanksalot,
Swapna
on November 2, 2007 at 11:41 am sandeep

hi thnnkas
on November 15, 2007 at 1:05 pm Juned

Thanks they help me a lot please do post more question and answer.
on November 16, 2007 at 3:27 am Nancy

Hello

Can you tell me please the function to split a name received in one field to first name, last name, middle name into separate fields?

Thanks very much!
on November 20, 2007 at 1:02 pm mushtaq

Thks pinal.

It will help for me & others.

regards
Mushtaaq
on November 26, 2007 at 6:44 pm Raghu

hi

very use full for me thanks pinl
on December 2, 2007 at 6:21 pm Senthil.G

hi

This is very useful for my interview preparation.If you know any new concepts.please post my email id.

Thanking you
on December 6, 2007 at 3:10 pm Femi

This is very helpful for me
on December 16, 2007 at 7:48 pm Sudhir

Dear sir,

the information given by you is very good and helpful
thankyou so much

sudhir
on December 18, 2007 at 6:13 pm Colo

VUI – VERY USEFUL INFORMATION. thumbs up !!!
on January 3, 2008 at 10:08 am Uma Lakshman

You are awesome.. I appreciate the amount of time you spend towards this blog which is so useful for many people like me. Keep up the good work! God Bless You ..
on January 12, 2008 at 1:39 pm Sameer Bhatnagar

Hi Pinal Dave…

I am Proud of you….
you are doing a very great Job…
All the Best for Your Future….

JAI HIND…
(Sabse aage Honge….Hindustani !!!!!!)
on January 14, 2008 at 2:37 pm Dhirendra Singh

hi

This is very useful for my interview preparation.If you know any new concepts.please post my email id.
Plz, send me sql server database notes.
Thanking you
on January 15, 2008 at 6:04 am Shrinivas

Hello! Sir,

Good evening.

I am thankful to you for this useful information, which helps me and to everybody…

Sure, u have important role in everybody’s success…

Thank you very much.
All the Best.

Shrinivas
on January 22, 2008 at 11:17 am vellingiri

This is very very useful for me.
on January 30, 2008 at 12:39 pm Jayaprabha

Hi,

This is awesome and really very useful those who preparing for their interview..

Thank you very much,
Jayaprabha.D
on February 2, 2008 at 7:30 pm J. Saraboji

Dear Sir,

Mostly I used name only, but now I used Sir.

I will pray for you to give more years to live in the same.

Thanks,
JSaraboji.
on February 11, 2008 at 10:04 am Naga

Excellent! The question and answers are great. I am looking for a job and It really helps me to prepare me for the Interview.

Thanks! Please keep updating this site.
on February 12, 2008 at 1:01 am Girish

Nice articles!

thanks,
on February 12, 2008 at 3:23 am koteswararao.kadiaym

Very good .I m following his articles for career growth in sql domain.
on February 13, 2008 at 11:00 am Preethi

Excellent!!!
on February 14, 2008 at 3:02 am Neethu

If possible please post with some examples. That may help us in interviews.
Thank you.
on February 28, 2008 at 4:47 pm Asane

Well…. Keep it up……
on March 10, 2008 at 2:32 pm Pooja Manocha

Hii,

Really liked it. Want a copy of all the qs and ans.
Can u plz send it at my mail id.

Thanx.
on March 12, 2008 at 2:59 pm Sriram

Hi Dave,
Its really a good initiative, keep going.
on March 28, 2008 at 11:56 am kiran kumar

thank u sir
on March 31, 2008 at 8:19 pm Deva

Superb
on April 2, 2008 at 11:48 am Preeti Soni

U have done a good jod keep it up & all the best…………
on April 11, 2008 at 1:01 pm Shishir

Thanks……… These questions and answers are of great help……………..
Thanks…..a lot
on April 12, 2008 at 3:39 pm sam

thanks
on April 15, 2008 at 6:39 pm prabha

Hi,

I need to know

How to add a query to remote sever?
on April 22, 2008 at 10:35 am hakeem

it is so great to have a question and answers in this aspect.i want you to help me send sql complete note
on April 24, 2008 at 1:38 pm Preeti Soni

hello,
i need to know how can i remove Alias in a view.
on May 9, 2008 at 12:50 pm gopal

nice for begginers
on May 9, 2008 at 8:35 pm GOPINATH

Hi,

This site is very useful and answers were given very clearly…
on May 9, 2008 at 8:36 pm GOPINATH

Thank u so much…
on May 27, 2008 at 3:24 pm Anil

Can you explain Normalisation with “Examples”…….
on June 6, 2008 at 7:33 am SDC

Um, I’m not sure this was meant to help people who know diddly to get jobs as senior DBAs, I think the idea was to put together some common questions one might want to ask candidates in an interview.

But I could be wrong.
on June 7, 2008 at 7:36 am bvreddy

sir thanks u very sir
I require the SQL server Questions
ok sir bye
on June 7, 2008 at 7:37 am bvreddy

thanku very much sir
on June 20, 2008 at 2:52 pm chendu

Dave,
This is an excellent effort, these questions are not only useful in an interview prespective but will also provide a definite insight of SQL for beginners. Hope to have much more questions like this in the future.

Cheers,
Chendu
on June 29, 2008 at 2:43 pm Vinit gaur

Hi Dave,

What is the diffrence between RDBMS & DBMS

is excel is a DBMS?
on June 30, 2008 at 1:33 pm janarthanan

Respected sir

your question is very brilliant . please send the other interview aptitude question for c and c++
on July 3, 2008 at 3:08 pm Majith

Excellent Information for all SQL SERVER fans
on July 17, 2008 at 8:18 pm Sunil panda

Sir,
Thanks sir your question is very Brilient. Please send the other inturview question for Vc# and Java
on July 18, 2008 at 2:53 pm Irshad

I Have Seen all the Question and Answer its Really Good Stuff but when the Candiadte Have experince then interviewer mostly asked about the Query Basically that stuff is only for the Fresher or 1 years Experience Candiate

Thahx
Irshad hasan
on July 19, 2008 at 12:23 pm Riti

Hello Pinal,

Nice questions. In fact i am interviewing people thru these Qs. These are really awesome. I am done with MCSD & a .net developer since 3.5years. I am so interested for SQL DBA. Please guide me how to process.

Waiting your reply.

Regards
~ Riti
on August 3, 2008 at 11:55 am DINESH BHARDWAJ(sundernagar)

hi dave,

you are doing nice job,
This is an excellent effort, these questions are not only useful in an interview prespective but will also provide a definite insight of SQL for beginners
on August 13, 2008 at 8:35 pm Harinath Reddy

It’s very very 98.3 guru
on August 26, 2008 at 6:47 am Lisa

You are the BEST, mate!
on September 20, 2008 at 11:36 am pinaldave

UPDATE : Interview Questions and Answers are now updated with SQL Server 2008 Questions and its answers. New Location : SQL Server 2008 Interview Questions and Answers.

Please continue with your questions and answers at new location.
on February 24, 2009 at 6:22 pm SQL SERVER - Database Interview Questions and Answers Complete List Journey to SQL Authority with Pinal Dave

[...] Server Interview Questions and Answers SQL Server Interview Questions and Answers – Introduction SQL Server Interview Questions and Answers – Part 1 SQL Server Interview Questions and Answers – Part 2 SQL Server Interview Questions and Answers – [...]