About the Series …
This article continues the series, MS Access for the
Business Environment. The primary focus of this series is an
examination of business uses for the MS Access relational database management
system. The series is designed to provide guidance in the practical application
of data and database concepts to meet specific needs in the business world. The
majority of the procedures I demonstrate in this article and going forward will
be undertaken within MS Access 2003, although most of the concepts that
we explore in the series will apply to earlier versions of MS Access, as well.
For more information on the series, as well as the hardware
/ software requirements to prepare for the tutorials we will undertake, please
see Tutorial
1: Create a Calculated Field with the
Expression Builder.
Introduction to this Tutorial
In the
lesson just before our last, Access
Query Techniques: Subqueries, Part I, we introduced subqueries within
the context of MS Access, and practiced their creation and use to help us to
meet an illustrative business need. As a part of our exploration of
subqueries, we examined the syntax surrounding the use of a straightforward
sample subquery, and then began a hands-on example of the use of a subquery in
a multi-step practice exercise. After evolving an initial query, we created a
second query, within which we nested the first, to demonstrate the operation of
a subquery in our practice exercise. We then discussed various aspects of the
results datasets that we obtained in each step of the practice examples.
In our last article, Access
Query Techniques: Using the TOP Keyword, we took a break from subqueries to examine the TOP
keyword, both to illustrate its use in meeting another illustrative business
need, and to prepare us for this lesson, where we will use the keyword in a
continuing exploration of subqueries. We overviewed the TOP keyword,
getting a taste of its operation in an undistracted scenario, and are now ready
to proceed to the creation of a subquery that leverages TOP to
illustrate more sophistication in the use of subqueries. We examined the syntax
surrounding the use of TOP, together with its "modifier"
keyword PERCENT, then performed practical examples of their uses to meet
illustrative business needs. Finally, we discussed the results datasets that
we obtained in each of the practice examples.
The objective of this lesson is
to further delve into MS Access subqueries to render results that are more
sophisticated for organizational information consumers. To accomplish this, we
will introduce the use of the TOP keyword within another subquery
scenario, in a series of steps that include:
- an examination of the syntax surrounding the use of the subquery;
-
details of a "real world" need that can be met with the
use of the TOP keyword in a subquery scenario; -
an examination of the operation of the TOP keyword within
the subquery; -
a brief discussion of the results datasets that we obtain in each
step of the practice example, and how they meet the business need objectives.
We will use the Northwind sample database that
installs with MS Access for purposes of this lesson, in an attempt to make our
discussion useful to virtually anyone who has access to the application.
