C# INTERVIEW QUESTIONS

Where is the output of TextWriterTraceListener redirected?

To the Console or a text file depending on the parameter passed to the constructor.How do you debug an ASP.NET Web application?Attach the aspnet_wp.exe process to the DbgClr debugger.

What are three test cases you should go through in unit testing?

1. Positive test cases (correct data, correct output).

2. Negative test cases (broken or missing data, proper handling).

3. Exception test cases (exceptions are thrown and caught properly).

Can you change the value of a variable while debugging a C# application?

Yes. If you are debugging via Visual Studio.NET, just go to Immediate window.

What is the role of the DataReader class in ADO.NET connections?

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.

What are advantages and disadvantages of Microsoft-provided data provider classes in ADO.NET?

SQLServer.NET data provider is high-speed and robust, but requires SQL Server license purchased from Microsoft. 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.

What is the wildcard character in SQL?

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%’.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.