###BeginCaseStudy###

Topic 3, Online Bookstore
Background
You are developing an online bookstore web application that will be used by your company’s
customers.
Technical Requirements
General requirements:
The web store application must be an ASP.NET MVC application
written in Visual Studio.
The application must connect to a Microsoft SQL database.
The GetTop100Books() method is mission critical and must return
data as quickly as possible. It should take advantage of fast,
forward-only, read-only methods of reading data.
The ImportBooks() method must keep a copy of the data that can
be accessed while new books are being imported without blocking
reads.
The Create MonthlyTotalsReport() method must lock the data and
prevent others from updating or inserting new rows until complete.
The college textbook area of the web application must get data
from a daily updated CSV file.
The children’s book area of the web application must get data
directly from a local database. It must use a connection string. It
must also support access to the stored procedures on the database.
Further, it is required to have strongly typed objects. Finally, it will
require access to databases from multiple vendors and needs to
support more than one-to-one mapping of database tables.
The cookbook functionality is contained within a client-side
application that must connect to the server using HTTP and
requires access to the data using JavaScript.
The BookApiController class must have a method that is able to
perform ad-hoc queries using OData.
The RESTful API of the bookstore must expose the following endpoints.

Application Structure

PurchaseOrders.xml

FeaturedBooks.xml

###EndCaseStudy###

You need to update the CreateMonthlyTotalsReports() method to use database transactions.
Which code segment should you use?

A.
SqlConnection.BeginTransaction(IsolationLevel.ReadCommitted);

B.
SqlConnection.BeginTransaction(IsolationLevel.ReadUnconwited);

C.
SqlConnection.BeginTransaction(IsolationLevel.Chaos);

D.
SqlConnection.BeginTransaction(IsolationLevel.Serializable);

Explanation:
* Scenario: The Create MonthlyTotalsReport() method must lock the data and prevent others from updating or
inserting new rows until complete.
* Serializable:
A range lock is placed on the DataSet, preventing other users from updating or inserting rows into the dataset
until the transaction is complete.