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SQL SERVER INTERVIEW QUESTIONS 2014 BOOKLET -9 By Mr.J.Venkatesan Prabu - Managing Director of Kaashiv Infotech

            
      SQL SERVER INTERVIEW QUESTIONS 2014- SET 9 By 
"Mr.J.Venkatesan Prabu" 

KAASHIV INFOTECH

     [ The  Asia, India & Tamil Nadu Book Of  Record Holders ]


                                                       
    SQL Server Interview Questions 2014
SQL  SERVER –Booklet 9
-         Gives you the interview tips for SQL Server

 SQL SERVER INTERVIEW QUESTIONS WITH ANSWERS 

1. How many files can a Database contain in SQL Server? How many types of data files exists in SQL Server? How many of those files can exist for a single database?
§  A Database can contain a maximum of 32,767 files.
§  There are Primarily 2 types of data files Primary data file and Secondary data file(s)
§  There can be only one Primary data file and multiple secondary data files as long as the total # of files is less than 32,767 files

2. What is DCL?
§  DCL stands for Data Control Language.

3. What are the commands used in DCL?
§  GRANT, DENY and REVOKE.

4. What is Fill Factor?
§  Fill Factor is a setting that is applicable to Indexes in SQL Server. The fill factor value determines how much data is written to an index page when it is created / rebuilt.

5. What is the default fill factor value?
§  By default the fill factor value is set to 0.

6. Where do you find the default Index fill factor and how to change it?
§  The easiest way to find and change the default fill factor value is from Management Studio, right-click the SQL Server and chooses properties. In the Server Properties, choose Database Settings, you should see the default fill factor value in the top section. You can change to a desired value there and click OK to save the changes.
§  The other option of viewing and changing this value is using sp_configure.

7. What is a system database and what is a user database?
§  System databases are the default databases that are installed when the SQL Server is installed. Basically there are 4 system databases: Master, MSDB, TempDB and Model. It is highly recommended that these databases are not modified or altered for smooth functioning of the SQL System.
§  A user database is a database that we create to store data and start working with the data.

8. What are the recovery models for a database?
§  There are 3 recovery models available for a database. Full, Bulk-Logged and Simple are the three recovery models available.

9. What is the importance of a recovery model?
§  Primarily, recovery model is chosen keeping in view the amount of data loss one can afford to. If one expects to have minimal or no data loss, choosing the Full recovery model is a good choice. Depending on the recovery model of a database, the behaviour of database log file changes. I would recommend you read more material on log backups and log file behaviour and so on to understand in depth

10. What is Replication?
§  Replication is a feature in SQL Server that helps us publish database objects and data and copy (replicate) it to one or more destinations. It is often considered as one of the High-Availability options. One of the advantages with Replication is that it can be configured on databases which are in simple recovery model.
11. What the different types of Replication and why are they used?

§  There are basically 3 types of replication: Snapshot, Transactional and Merge Replication. The type of Replication you choose depends on the requirements and/or the goals one is trying to achieve. For example Snapshot Replication is useful only when the data inside the tables does not change frequently and the amount of data is not too large, such as a monthly summary table or a product list table etc. Transactional Replication would useful when maintaining a copy of a transactional table such as sales order tables etc. Merge Replication is more useful in case of remote / distributed systems where the data flow can be from multiple sites, for example sales done at promotional events which might not be connected to the central servers always.

12. What the different components in Replication and what is their use?

§  The 3 main components in Replication are Publisher, Distributor and Subscriber. Publisher is the data source of a publication. Distributor is responsible for distributing the database objects to one or more destinations. Subscriber is the destination where the publisher’s data is copied / replicated.


13. What the different Topologies in which Replication can be configured?

§  Replication can be configured in any topology depending keeping in view of the complexity and the workload of the entire Replication. It can be any of the following:

§  Publisher, Distributor and Subscriber on the same SQL Instance.
§  Publisher and Distributor on the same SQL Instance and Subscriber on a separate Instance.
§  Publisher, Distributor and Subscriber on individual SQL Instances.

14. How do you open a Cluster Administrator?

§  From Start -> Run and type CluAdmin (case insensitive) and the Cluster Administrator console is displayed OR you can also go to Start -> All programs -> Administrative Tools -> Cluster Administrator

15. What are the different ways you can create Databases in SQL Server?

§  T-SQL; Create Database command.
§  Using Management Studio
§  Restoring a database backup
§  Copy Database wizard

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Day
Programme
Day 1
Embedded System  (Embedded Program Designing ,Chip Burning)
Day 2
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Day 3
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Day 4
Ethical Hacking  (Facebook Hack,Server/Website Hacking(20 Attacks)
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Day
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Day 1
Aircraft Designing
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My T-SQL Gallery @code.msdn.microsoft


Created my own T-SQL Gallery in Microsoft site. Do visit the same and share your feedback,

http://code.msdn.microsoft.com/VenkatSQLSample/Thread/List.aspx

Thanks and Regards,
Venkatesan Prabu .J

SQL Server Interview questions - Part 1

What is the significance of NULL value and why should we avoid permitting null values?
Null means no entry has been made. It implies that the value is either unknown or undefined.We should avoid permitting null values because Column with NULL values can't have PRIMARY KEY constraints. Certain calculations can be inaccurate if NULL columns are involved.

What is SQL whats its uses and its component ?
The Structured Query Language (SQL) is foundation for all relational database systems. Most of the large-scale databases use the SQL to define all user and administrator interactions. It enable us to retrieve the data from based on our exact requirement. We will be given a flexibility to store the data in our own format.


The DML component of SQL comprises four basic statements:
* SELECT to get rows from tables
* UPDATE to update the rows of tables
* DELETE to remove rows from tables
* INSERT to add new rows to tables


What is DTS in SQL Server ?
Data Transformation Services is used to transfer the data from one source to our required destination. Considering am having some data in sql server and I need to transfer the data to Excel destination. Its highly possible with dialogue based tool called Data Transformation services. More customization can be achieved using SSIS. A specialized tool used to do such migration works.


What is the difference between SQL and Pl/Sql ?

Straight forward. SQL is a single statement to finish up our work.Considering, I need some data from a particular table. “Select * from table” will fetch the necessary information. Where as I need to do some row by row processing. In that case, we need to go for Procedural Logic / SQL.

What is the significance of NULL value and why should we avoid permitting null values?
Null means no entry has been made. It implies that the value is either unknown or undefined.We should avoid permitting null values because Column with NULL values can't have PRIMARY KEY constraints. Certain calculations can be inaccurate if NULL columns are involved.

Difference between primary key and Unique key?
Both constraints will share a common property called uniqueness. The data in the column should be unique. The basic difference is,
· Primary key won’t allow null value. Whereas, unique key will accept null value but only one null value.
· On creating primary key, it will automatically format the data inturn creates clustered index on the table. Whereas, this characteristics is not associated with unique key.
· Only one primary key can be created for the table. Any number of Unique key can be created for the table.

Select Statement in SQL Server

Select Statement in SQL Server

String Functions in sql server

String Functions in sql server
Substring/Len/replace/Ltrim/Rtrim

SQL Server Interview Question - Part 2

What is normalization?

Normalization is the basic concept used in designing a database. Its nothing but, an advise given to the database to have minimal repetition of data, highly structured, highly secured, easy to retrieve. In high level definition, the Process of organizing data into tables is referred to as normalization.


What is a stored procedure:
Stored procedures are precompiled T-SQL statements combined to perform a single task of several tasks. Its basically like a Macro so when you invoke the Stored procedure, you actually run a set of statements. As, its precompiled statement, execution of Stored procedure is compatatively high when compared to an ordinary T-SQL statement.


What is the difference between UNION ALL Statement and UNION ?
The main difference between UNION ALL statement and UNION is UNION All statement is much faster than UNION,the reason behind this is that because UNION ALL statement does not look for duplicate rows, but on the other hand UNION statement does look for duplicate rows, whether or not they exist.

Example for Stored Procedure?
They are three kinds of stored procedures,1.System stored procedure – Start with sp_2. User defined stored procedure – SP created by the user.3. Extended stored procedure – SP used to invoke a process in the external systems.Example for system stored proceduresp_helpdb - Database and its propertiessp_who2 – Gives details about the current user connected to your system. sp_renamedb – Enable you to rename your database


What is a trigger?

Triggers are precompiled statements similar to Stored Procedure. It will automatically invoke for a particular operation. Triggers are basically used to implement business rules.


What is a view?
If we have several tables in a db and we want to view only specific columns from specific tables we can go for views. It would also suffice the needs of security some times allowing specfic users to see only specific columns based on the permission that we can configure on the view. Views also reduce the effort that is required for writing queries to access specific columns every time.


What is an Index?
When queries are run against a db, an index on that db basically helps in the way the data is sorted to process the query for faster and data retrievals are much faster when we have an index.


What are the types of indexes available with SQL Server?

There are basically two types of indexes that we use with the SQL ServerClustered -

1. It will format the entire table, inturn physically sort the table.

2. Only one clustered index can be created for a table.

3. Data will be located in the leaf level.

4. By default, primary key will create clustered index on the table.

Non-Clustered Index

1. It wont touch the structure of the table.

2. It forms an index table as reference to the exact data.

3. A reference to the data will be located in the leaf level.

4. For a table, we can create 249 non clustered index.

Happy Learning!!!
Regards,
Venkatesan Prabu .J

SQL Interview question

Extent Vs Page?

Pages are low level unit to store the exact data in sql server. Basically, the data will be stored in the mdf, ldf, ndf files. Inturn, pages are logical units available in sql server.The size of the page is 8KB.

Eight consecutive pages will form an extent 8 * 8KB = 64KB.

Thus I/O level operation will be happening at pages level.The pages will hold a template information at the start of each page (header of the page).

They are,

1. page number,

2. page type,

3. the amount of free space on the page,

4. the allocation unit ID of the object that owns the page.

Extents will be classifed into two types,

1. Uniform extents

2. Mixed extents

Uniform Extents:It occupied or used by a single object. Inturn, a single object will hold the entire 8 pages.Mixed

Extents:Mulitple objects will use the same extent. SQL Server will allow a max of eight objects to use a shared extent.

Property of SQL Server :Initally if an object is created, sql server will allocate the object to the mixed extent and once if the size reaches 8 pages and more... immediately, a new uniform extent will be provided for that particular object.

Herecomes, our fragmentation and reindexing concepts.

Best Joke - Enjoy it

Best Joke - Enjoy it