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Question 16 :

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

Answer :

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.


Question 17 :

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

Answer :

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.


Question 18 :

What is the wildcard character in SQL?

Answer :

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%'.


Question 19 :

Explain ACID rule of thumb for transactions?

Answer :

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.


Question 20 :

What connections does Microsoft SQL Server support?

Answer :

Windows Authentication (via Active Directory) and SQL Server authentication (via Microsoft SQL Server username and password).