1. 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, but it’s a .NET layer on top of OLE layer,
so not the fastest thing in the
world. ODBC.NET is a deprecated layer provided for backward compatibility to
ODBC engines.
2. What’s the role of the DataReader class in ADO.NET connections?
It returns a read-only
dataset from the data source when the command is executed.
3. 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%’.
4. Explain ACID rule of thumb for transactions. Transaction
must be Atomic (it is one unit of
work and does not dependent on previous and following transactions), Consistent
(data is either
committed or roll back, no “in-between” case where something has
been updated and something hasn’t),
Isolated (no transaction sees the intermediate results of the current transaction),
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? Windows
Authentication (via
Active Directory) and SQL Server authentication (via Microsoft SQL Server username
and passwords).
6. Which one is trusted and which one is untrusted? 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 transaction.
7. Why would you use untrusted verificaion? Web Services might
use it, as well as non-
Windows applications.
8. What does the parameter Initial Catalog define inside Connection
String? The database
name to connect to.
9. What’s the data provider name to connect to Access database? Microsoft.Access.
10. What does Dispose method do with the connection object? Deletes it from the memory.
11. What is a pre-requisite for connection pooling? Multiple
processes must agree that they will
share the same connection, where every parameter is the same, including the
security settings.
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