Questions on XML, ADO.NET etc

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C# General Interview Questions

C# Questions on properties, events etc

Questions on XML, ADO.NET etc

C# Rapid Fire Questions 1

C# Rapid Fire Questions 2

SQL Interview Questions 1

SQL Interview Questions 2

































XML Documentation Questions
1.Is XML case-sensitive?
Ans. Yes.
2.What’s the difference between // comments,
/* */ comments and /// comments?
Ans. Single-line comments, multi-line comments,
and XML documentation comments.
3.How do you generate documentation from the C#
file commented properly with a command-line compiler?
Ans. Compile it with the /doc switch.
Debugging and Testing Questions
What debugging tools come with the .NET SDK?
1. CorDBG – command-line debugger.  To use
CorDbg, you must compile the original C# file
using the /debug switch.

2. DbgCLR – graphic debugger.  Visual Studio
.NET uses the DbgCLR.
2.What does assert() method do?
Ans. In debug compilation, assert takes in a Boolean
condition as a parameter, and shows the error
dialog if the condition is false.  The program proceeds
without any interruption if the condition is true.
3.What’s the difference between the Debug class
and Trace class?
Ans. Documentation looks the same. Use Debug class for
debug builds, use Trace class for both debug and release
4.Why are there five tracing levels in System.Diagnostics.TraceSwitcher?
Ans. The tracing dumps can be quite verbose.  For
applications that are constantly running you run the
risk of overloading the machine and the hard drive. 
Five levels range from None to Verbose, allowing you to
fine-tune the tracing activities.
5.Where is the output of TextWriterTraceListener
Ans. To the Console or a text file depending on
the parameter passed to the constructor.
6.How do you debug an ASP.NET Web application?
Ans. Attach the aspnet_wp.exe process to the
DbgClr debugger.
7.What are three test cases you should go through
in unit testing?
1.       Positive test cases (correct data, correct
2.       Negative test cases (broken or missing data,
proper handling).
3.       Exception test cases (exceptions are thrown
and caught properly).
8.Can you change the value of a variable while debugging
a C# application?
Ans. Yes.  If you are debugging via Visual Studio.NET,
just go to Immediate window.
ADO.NET and Database Questions
 What is the role of the DataReader class in
ADO.NET connections?
Ans. It returns a read-only, forward-only rowset from
the data source.  A DataReader provides fast access
when a forward-only sequential read is needed.
2.What are advantages and disadvantages of Microsoft
provided data provider classes in ADO.NET?
Ans. SQLServer.NET data provider is high-speed and
robust, but requires SQL Server license purchased from

OLE-DB.NET is universal for accessing other sources,
like Oracle, DB2, Microsoft Access and Informix. 
OLE-DB.NET is a .NET layer on top of the OLE layer, so
it’s not as fastest and efficient as SqlServer.NET.
3.What is the wildcard character in SQL?
Ans. Let’s say you want to query database with LIKE for
all employees whose name starts with La. The wildcard
character is %, the proper query with LIKE would
involve ‘La%’.
4.Explain ACID rule of thumb for transactions.
A transaction must be:
1.Atomic - it is one unit of work and does not dependent
on previous and following transactions.
2.Consistent - data is either committed or roll back, no
“in-between” case where something has been updated and
something hasn’t.
3.Isolated - no transaction sees the intermediate results
of the current transaction).
4.Durable - the values persist if the data had been
committed even if the system crashes right after.
5.What connections does Microsoft SQL Server support?
Ans. Windows Authentication (via Active Directory) and
SQL Server authentication (via Microsoft SQL Server
username and password).
6.Between Windows Authentication and SQL Server
Authentication, which one is trusted and which one is
Ans. Windows Authentication is trusted because the
username and password are checked with the Active
Directory, the SQL Server authentication is untrusted,
since SQL Server is the only verifier participating in the
7.What does the Initial Catalog parameter define in the
connection string?
Ans. The database name to connect to.
8.What does the Dispose method do with the connection
Ans. Deletes it from the memory.
To Do: answer better.  The current answer is not entirely
9.What is a pre-requisite for connection pooling?
Ans. Multiple processes must agree that they will share
the same connection, where every parameter is the same,
including the security settings.  The connection string
must be identical.
Assembly Questions
How is the DLL Hell problem solved in .NET?
Ans. Assembly versioning allows the application to specify
not only the library it needs to run (which was available
under Win32), but also the version of the assembly.
2.What are the ways to deploy an assembly?
Ans. An MSI installer, a CAB archive, and XCOPY command.
3.What is a satellite assembly?
Ans. When you write a multilingual or multi-cultural
application in .NET, and want to distribute the core
application separately from the localized modules, the
localized assemblies that modify the core application
are called satellite assemblies.
4.What namespaces are necessary to create a localized
Ans.System.Globalization and System.Resources.
5.What is the smallest unit of execution in .NET?
Ans. an Assembly.
6.When should you call the garbage collector in .NET?
Ans. As a good rule, you should not call the garbage
collector.  However, you could call the garbage collector
when you are done using a large object (or set of objects)
to force the garbage collector to dispose of those very
large objects from memory.  However, this is usually not a
good practice.
7.How do you convert a value-type to a reference-type?
Ans. Use Boxing.
8.What happens in memory when you Box and Unbox a
Ans. Boxing converts a value-type to a reference-type, thus
storing the object on the heap.  Unboxing converts a

reference-type to a value-type, thus storing the value on
the stack.