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Unit 6: VB Control Structure

7. Variables are rarely declared inside an If ... Then block or a Select Case block. If so, such
a variable has block-level scope; that is, the variable cannot be referred to by code outside
of the block.

Wroba Case Study
The WROBA (WRox Online Banking Application) case study used in this book uses a theme
you may be familiar with—Online banking. In fact, what we are going to develop during the
first part of the book is a desktop based application—it still counts as online, in that it will
enable a user sitting at their desk to carry out various banking activities, even though it will
have a Visual Basic form type user interface.
The functionality of the case study was arrived at by careful analysis of the business
requirements of a hypothetical client (Big Bank) and this is covered in Chapter 6. But so we’re
all clear about where we are heading, let’s highlight some of the major parts of WROBA.
There are two sides to the application;
a customer side and an administration side.
The customer side will:
• Show the status of the users accounts (two accounts are permissible Checking and
Saving, but only one of each per card)
• Allow previous transactions to be viewed
• Allow user passwords to be changed
• Allow users to add or edit payee details
• Allow users to move money between accounts
• Allow users to pay bills to payees

The administration side of the application offers a separate login for designated
administrators, and allows the administrator to:
• Add and delete new accounts (as represented by cards)
• Lock and unlock cards that have fallen foul either of the login system (too many wrong
login attempts) or the banking authorities
• Add and edit back details (this feature is not fully implemented in our fledgling
application) Let’s have a look at how this initial version relates to the 3-tier architecture
we’ve previously looked at:
The data tier consists of two units–a SQL Server 7.0 database (called Big Bank) that contains
both data and stored procedures for accessing and operating on that data, and the Bank_DB.
Dll component.
The business tier consists of one COM component–Bank_Bus.dll.
The user tier functionality is provided by Bank_UI.exe–although it could be split into two
projects, we have dealt with it as one.

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