SQL Interview Questions

1. What is Distributed Queries in SQL Server?


Distributed queries access data from multiple heterogeneous data sources. These data sources can be stored on either the same or different computers. Microsoft SQL Server supports distributed queries by using OLE DB.

SQL Server users can use distributed queries to access the following:

#. Distributed data stored in multiple instances of SQL Server.
#. Heterogeneous data stored in various relational and nonrelational data sources accessed by using an OLE DB provider.

2. What is the use of Keyword WITH ENCRYPTION keyword in SQL Server?

WITH ENCRYPTION keyword is used to encrypt the text of the Stored Procedure.

Once SPs are encrypted, the original text of the SP are not visible. User who has created the SP will need to save the text to be used to create SP somewhere safe to reuse it again or Users that have access to system tables or database files can retrieve the encrypted text.


3. What is user-defined functions in SQL Server?

User-Defined Functions allows to define custom T-SQL functions that can accept zero or more parameters and return a single scalar data value or a table data type.

In terms of functionality it is similar to C# or VB.NET functions except the fact that code is written in T-SQL.


4. What is user-defined data type in SQL Server?

User-defined data types can be used when several tables must store the same type of data in a column and you must ensure that these columns have exactly the same data type, length, and nullability.



5. What is a tuple?

A tuple is an instance of data within a relational database


6. What is the use of bit data type and what kind of data is stored into it?

Bit datatype is used to store boolean information like 1 or 0 where 1 is considered as true and 0 is considered as false.


While querying the database we need to use 1 or 0 in the select statement to filter out the data instead of true and false.



7. What is blocking in SQL Server?

Blocking in SQL Server is a scenario where one connection to SQL Server locks one or more records, and a second connection to SQL Server requires a conflicting lock type on the record or records locked by the first connection. This causes the second connection to wait until the first connection releases its locks. By default, a connection will wait an unlimited amount of time for the blocking lock to go away.


8. Difference between varchar and char:

varchar are variable length strings with a maximum length specified. If a string is less than the maximum length, then it is stored verbatim without any extra characters.
char are fixed length strings with a set length specified. If a string is less than the set length, then it is padded with extra characters so that it's length is the set length.

Use varchar when your strings do not have a fixed length (e.g. names, cities, etc.)

Use char when your strings are always going to be the same length (e.g. phone numbers, zip codes, etc)


9. Can we create a Foreign Key with out Primary Key?

Yes. If the table has Unique Key then it is possible to create a Foreign Constraint.


10. What is Check Constraint?


Check constraint specifies a condition that is enforced for each row of the table on which the constraint is defined. Once constraint is defined, insert or update to the data within the tables is checked against the defined constraint.


11. How to get GUID in sql server?

select newid().
This will return you GUID


12. What is DTC?

The Microsoft Distributed Transaction Coordinator (MS DTC) is a transaction manager that allows client applications to include several different sources of data in one transaction. MS DTC coordinates committing the distributed transaction across all the servers enlisted in the transaction


13. What are three SQL keywords used to change or set someone’s permissions?

Grant, Deny and Revoke

14. What is Log Shipping?

In Microsoft SQL Server, you can use log shipping to feed transaction logs from one database to another on a constant basis. Continually backing up the transaction logs from a source database and then copying and restoring the logs to a destination database keeps the destination database synchronized with the source database. This allows you to have a backup server and also provides a way to offload query processing from the main computer (the source server) to read-only destination servers

15. What is DTS?

DTS is a set of tools you can use to import, export, and transform heterogeneous data between one or more data sources, such as Microsoft SQL Server, Microsoft Excel, or Microsoft Access. Connectivity is provided through OLE DB, an open-standard for data access. ODBC (Open Database Connectivity) data sources are supported through the OLE DB Provider for ODBC.

Dotnet Interview Questions

1.Describe the role of inetinfo.exe, aspnet_isapi.dll andaspnet_wp.exe in thepage loading process inetinfo.exe is theMicrosoft IIS server running, handling ASP.NET requests among other things.When an ASP.NET request is received

(usually a file with .aspx extension),the ISAPI filter aspnet_isapi.dll takes care of it by passing the request tothe actual worker process aspnet_wp.exe.

2. What’s the difference between Response.Write()
andResponse.Output.Write()?

The latter one allows you to write formattedoutput.

3. What methods are fired during the page load?

Init() - when the pageis instantiated, Load() - when the page is loaded into server memory,PreRender() - the brief moment before the page is displayed to the user asHTML, Unload() -when page finishes loading.

4. Where does the Web page belong in the .NET Framework class
hierarchy?

System.Web.UI.Page

5. Where do you store the information about the user’s locale?

System.Web.UI.Page.Culture

6. What’s the difference between Codebehind="MyCode.aspx.cs"
andSrc="MyCode.aspx.cs"?

CodeBehind is relevant to Visual Studio.NET only.

7. What’s a bubbled event? When you have a complex control, like DataGrid,
writing an event processing routine for each object (cell, button, row, etc.) is
quite tedious.

The controls can bubble up their eventhandlers, allowing the main
DataGrid event handler to take care of its constituents.

8. Suppose you want a certain ASP.NET function executed on MouseOver
overa certain button. Where do you add an event handler?

It’s the
Attributesproperty, the Add function inside that property. So
btnSubmit.Attributes.Add("onMouseOver","someClientCode();")

9. What data type does the RangeValidator control support?

Integer,String and Date.
10. Explain the differences between Server-side and Client-side code? Serverside code runs on the server.

Client-side code runs in the clients’ browser.

11. What type of code (server or client) is found in a Code-Behind class?

Server-side code.

12. Should validation (did the user enter a real date) occur server-side or
client-side? Why?

Client-side. This reduces an additional request to the server

to validate the users input.
13. What does the "EnableViewState" property do? Why would I want it on oroff?

It enables the viewstate on the page. It allows the page to save the users
input on a form.

14. What is the difference between Server.Transfer and Response.Redirect?

Why would I choose one over the other? Server.Transfer is used to post aform to another page. Response.Redirect is used to redirect the user to another page or site.

15. Can you explain the difference between an ADO.NET Dataset and an ADO Recordset?

•?A DataSet can represent an entire relational database in memory,
complete with tables, relations, and views.
•?A DataSet is designed to work without any continuing connection to
the original data source.
•?Data in a DataSet is bulk-loaded, rather than being loaded on
demand.
•?There's no concept of cursor types in a DataSet.
•?DataSets have no current record pointer You can use For Each
loops to move through the data.
•?You can store many edits in a DataSet, and write them to the
original data source in a single operation.
•?Though the DataSet is universal, other objects in ADO.NET come in
different versions for different data sources.

16. Can you give an example of what might be best suited to place in the
Application_Start and Session_Start subroutines?

This is where you can set
the specific variables for the Application and Session objects
.
17. If I’m developing an application that must accommodate multiple securitylevels though secure login and my ASP.NET web application is spannedacross three web-servers (using round-robin load balancing) what would bethe best approach to maintain login-in state for the users?

Maintain the login state security through a database.

18. Can you explain what inheritance is and an example of when you might use it?

When you want to inherit (use the functionality of) another class. Base Class Employee. A Manager class could be derived from the Employee base class.

19. Whats an assembly?

Assemblies are the building blocks of the .NET framework. Overview of assemblies from MSDN

20. Describe the difference between inline and code behind.

Inline code written along side the html in a page. Code-behind is code written in a separate file and referenced by the .aspx page.

21. Explain what a diffgram is, and a good use for one?

The DiffGram is one of the two XML formats that you can use to render DataSet object contents to
XML. For reading database data to an XML file to be sent to a Web Service.

22. Whats MSIL, and why should my developers need an appreciation of it if at all?

MSIL is the Microsoft Intermediate Language. All .NET compatible
languages will get converted to MSIL.

23. Which method do you invoke on the DataAdapter control to load your
generated dataset with data?

The .Fill() method

24. Can you edit data in the Repeater control?

No, it just reads the information from its data source

25. Which template must you provide, in order to display data in a Repeater
control?

ItemTemplate

26. How can you provide an alternating color scheme in a Repeater control?

Use the AlternatingItemTemplate

27. What property must you set, and what method must you call in your code,in order to bind the data from some data source to the Repeater control?

You must set the DataSource property and call the DataBind method.

28. What base class do all Web Forms inherit from?

The Page class.

29. Name two properties common in every validation control?

ControlToValidate property and Text property.

30. What tags do you need to add within the asp:datagrid tags to bind columns manually?

Set AutoGenerateColumns Property to false on the datagrid tag

31. What tag do you use to add a hyperlink column to the DataGrid?

32. What is the transport protocol you use to call a Web service?

SOAP is the preferred protocol.

33. True or False: A Web service can only be written in .NET?

False

34. What does WSDL stand for?

(Web Services Description Language)

35. Where on the Internet would you look for Web services?

(http://www.uddi.org)

36. Which property on a Combo Box do you set with a column name, prior to setting the DataSource, to display data in the combo box?

DataTextField
property

37. Which control would you use if you needed to make sure the values in two different controls matched?

CompareValidator Control

38. True or False: To test a Web service you must create a windows application or Web application to consume this service?

False, the webservice comes with a test page and it provides HTTP-GET method to test.

39. How many classes can a single .NET DLL contain?

It can contain many classes.

ASP.NET Interview Questions

1. Describe the difference between inline and code behind.?

Inline code written along side the html in a page. Code-behind is code written in a separate file and referenced by the .aspx page.

2. Explain what a diffgram is, and a good use for one?

The DiffGram is one of the two XML formats that you can use to render DataSet object contents to XML. For reading database data to an XML file to be sent to a Web Service.


3. Whats MSIL, and why should my developers need an appreciation of it if at all?

MSIL is the Microsoft Intermediate Language. All .NET compatible languages will get converted to MSIL.

4. Which method do you invoke on the DataAdapter control to load your generated dataset with data?

The .Fill() method

5. Can you edit data in the Repeater control?

No, it just reads the information from its data source

6. Which template must you provide, in order to display data in a Repeater control?

ItemTemplate

7. How can you provide an alternating color scheme in a Repeater control?

Use the AlternatingItemTemplate

8. What property must you set, and what method must you call in your code, in order to bind the data from some data source to the Repeater control?

You must set the DataSource property and call the DataBind method.

9. What base class do all Web Forms inherit from?

The Page class.

10. Name two properties common in every validation control?

ControlToValidate property and Text property.

11. What tags do you need to add within the asp:datagrid tags to bind columns manually?

Set AutoGenerateColumns Property to false on the datagrid tag

12. What tag do you use to add a hyperlink column to the DataGrid?



13. What is the transport protocol you use to call a Web service?

SOAP is the preferred protocol.

14. True or False: A Web service can only be written in .NET?

False

15. What does WSDL stand for?

(Web Services Description Language)

16. Which property on a Combo Box do you set with a column name, prior to setting the DataSource, to display data in the combo box?

DataTextField property

17. Which control would you use if you needed to make sure the values in two different controls matched?

CompareValidator Control

18. True or False: To test a Web service you must create a windows application or Web application to consume this service?

False, the webservice comes with a test page and it provides HTTP-GET method to test.

19. How many classes can a single .NET DLL contain?

It can contain many classes.

What is Ajax?

The term Ajax was coined by Jesse James Garrett and is a short form for "Asynchronous Javascript and XML". Ajax represents a set of commonly used techniques, like HTML/XHTML, CSS, Document Object Model(DOM), XML/XSLT, Javascript and the XMLHttpRequest object, to create RIA's (Rich Internet Applications).
Ajax gives the user, the ability to dynamically and asynchronously interact with a web server, without using a plug-in or without compromising on the user’s ability to interact with the page. This is possible due to an object found in browsers called the XMLHttpRequest object.

Explain WCF ?

In Simple words, WPF stands for Windows Presentation Foundation.

In detailed view WPF is a new library to create the UI for smart client applications. Most noteable point is : application does not use Window handles. It is easy to resize the UI and supports sound video.


Definition of WPF is : Windows Presentation Foundation (WPF) is Microsoft's development tool for Web applications and rich client applications.With WPF, developers can use XAML, the Extensible Application Markup Language, to create custom controls, graphics, 3D images and animations that are not available in traditional HTML implementations.

Explain WPF?

n Simple words, WPF stands for Windows Presentation Foundation.

In detailed view WPF is a new library to create the UI for smart client applications. Most noteable point is : application does not use Window handles. It is easy to resize the UI and supports sound video.


Definition of WPF is : Windows Presentation Foundation (WPF) is Microsoft's development tool for Web applications and rich client applications.With WPF, developers can use XAML, the Extensible Application Markup Language, to create custom controls, graphics, 3D images and animations that are not available in traditional HTML implementations.

What is the role of a ScriptManagerProxy?

A page can contain only one ScriptManager control. If you have a Master-Content page scenario in your application and the MasterPage contains a ScriptManager control, then you can use the ScriptManagerProxy control to add scripts to content pages.

Also, if you come across a scenario where only a few pages in your application need to register to a script or a web service, then its best to remove them from the ScriptManager control and add them to individual pages, by using the ScriptManagerProxy control. That is because if you added the scripts using the ScriptManager on the Master Page, then these items will be downloaded on each page that derives from the MasterPage, even if they are not needed, which would lead to a waste of resources.

disadvantage of ajax related to browser integration?

Dynamically created pages created by ajax does not support back button which takes the user to the previous pages. There are various solutions to this problem out of which one solution is to use iframes. Also users can bookmark a certain application in its state. User can maintain the applications as the state of the application changes

Explain security of the Ajax based web applications?

The XMLHttpRequest object is subjected to the browsers security
sandbox. Any resources requested by the XMLHttpRequest object must reside within the same domain from which the calling script originated from which the calling script requested. XMLHttpRequest cannot request services due to security restriction, outside the domain from which the script was originally served.

How do you invoke a web method of web service in AJAX?

In order to use a webmethod of a webservice, we need to add the reference of webservice in the section of ScriptManager. Under services you have to configure the servicepath.

< asp:ScriptManager ID="ScriptManager1" runat="server">
< Services>
< asp:ServiceReference Path="..\service1.asmx" />
< /Services>
< /asp:ScriptManager>

Inside JAvascript Use methods of this service directly like
service1.methodname()