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VIEWS AND STORED QUERIES
Running head: THE PURPOSE OF CREATING SQL SERVER 2000 VIEWS
The Purpose of Creating SQL Server 2000 Views, also known as a
Stored Query, and How Views Can Enhance Database Security.
Unit 2 Discussion Board Assignment
Ignatius C. Spots
Carnegie-Mellon University
Database Design and Implementation
ITS610-02
Professor Archie Addo, Ph.D.
November 25, 2003
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VIEWS AND STORED QUERIES
Abstract
This paper will describe some of the various uses for stored
queries, also known as database views.
This paper will focus on
how views fulfill the need of data users to access pertinent
data in a convenient manner while allowing data owners to
maintain the security of sensitive data that may be contained in
the same or adjoining tables.
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VIEWS AND STORED QUERIES
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The Purpose of Creating SQL Server 2000 Views, also known as a
Stored Query, and How Views Can Enhance Database Security.
A Structured Query Language (SQL) view, also known as a
stored query, can be created for many purposes. By drawing upon
key columns and rows of data, views can be used to summarize
data into a condensed and concise form.
Views can also be used
to restrict access to data by hiding sensitive columns and rows
from those who do not have a “need to know.”
Even the criteria
for creating a view can be hidden from users, by using encrypted
views. (Dewson, R., 2002).
Such would be the case if you did
not want any users to know what methods were used to derive
certain data (in order to obscure how – and from where – the
data came).
Views can be based upon columns and row in one
table or many tables.
Views can be based upon data in one
database or in several databases (distributed views).
be based upon other views.
Views can
Views can be saved (as a stored
query) and re-used over and over again.
“…a view is a virtual table whose contents are defined
by a query.
Like a real table, a view consists of a set of
named columns and rows of data.
However, a view does not
exist as a stored set of data values in a database.
The
rows and columns of data come from tables referenced in the
query defining the view and are produced dynamically when
the view is referenced…”
(Microsoft, 2000).
VIEWS AND STORED QUERIES
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The flexibility of views allows this structure to be used
for many different purposes.
Some examples follow.
Web-based front-end applications are very popular, due to
the fact that they lack the requirement for any proprietary
client software.
In an n-tiered application, the web-based
front end application (1st tier) accesses data from middleware
(2nd tier - that applies business rules and/or business logic to
the process) and the middleware accesses a database (3rd tier) as
its back-end component.
For anonymous users who reference
information from a web browser, views can be used to present
summarized data that does not include any personal or sensitive
data.
Such a case would be needed with public users accessing
US census data on a public web site sponsored by a federal
agency.
In this situation a view is essential to allow limited
access to a subset of the collected data that that should be
made available to the general public, by law.
In a corporate situation, those who deal with personnel
information may be restricted from viewing financial data on
employees, including salary data, commissions, and end-of-theyear bonuses.
Database views can facilitate limited access to
non-financial information on employees, while restricting access
to all other information.
In a military environment, where information is categorized
as non-classified, classified, secret, and top-secret, those
with the proper clearance would be able to view rows of data
that met, but did not exceed, the clearance and corresponding
classification of the viewer.
Views help to implement the
VIEWS AND STORED QUERIES
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security, in this situation, that is needed to protect
classified information.
In an educational situation, those responsible for updating
student records can be kept from updating employee records, in a
similar manner, by the use of views.
Views can facilitate the
work that employees need to do to accomplish their job, while
protecting data that may be contained in the same database and
the same tables; data that should not be updated by the
employees (i.e. their own salaries, vacation time, etc.).
A view can save a considerable amount of re-programming and
re-work, for instance, by acting as a global search and replace
mechanism.
A view can be defined to present rows and columns of
data that meet only a certain criteria, such as the set of raw
materials (i.e. carbon) used in the manufacture of a finished
product (i.e. composite material used to make the skin of the
fighter jets/aircraft).
Once a view is presented containing the
records and columns meeting the specific criteria, these records
can systematically or mathematically be updated to reflect an
increase in the cost of these raw materials.
This would allow
an update to selected records without the need to re-program an
entire database or database application.
Similarly, a view can be re-used in different situations,
such as the display of critical business information for
different sales regions, without the need to completely redefine or re-program an application.
The view can be “re-
targeted” to a different region’s database, and little or no reprogramming is necessary to draw out the same type of
VIEWS AND STORED QUERIES
information about the strategic information relating to widely
spread geographical business regions.
As you can see, views present a convenient mechanism for
the purpose of organizing and presenting information contained
in a relational database.
This is all done without the need to
store the pertinent data separately from the source data.
Since
views have most of the capabilities of tables, then most of the
functions that you would perform on a table can be performed on
a view.
data.
Views are very efficient, since views do not replicate
Because of the fact that only the queries that establish
a view are stored in the database tables, views do not have to
take up a lot of room.
Views can be indexed, which does
increase their storage requirement, but this performance feature
is more that offset by the savings in “wait” time and increase
in access speed that it affords.
The use of views should be
considered in any situation that requires limited access to data
by multiple people.
When used in conjunction with integrity
controls, authorization rules, user-defined procedures,
encryption, and authentication schemes (Hoffer, J. A., et. al.,
2002), database views help to enhance the security of any
database while allowing [limited] access to necessary
information. Typically, database applications use a very large
number of view.
In summary, views are mainly used for three purposes:
 As a security measure by restricting users to certain rows
and columns
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VIEWS AND STORED QUERIES
 As a method of joining data from multiple tables and
presenting it as if it resides in one table
 To return summary data instead of detailed data (Dewson, R.,
2002).
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VIEWS AND STORED QUERIES
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References
Dewson, R. (2002). Beginning SQL Server 2000 Programming. Wrox
Press. Birmingham, UK. 1st Ed. Pp. 489-518.
Hoffer, J. A., et. al. (2002).
Modern Database Management.
Pearson Education, Inc. Upper Saddle River, New Jersey. 6th
Ed. Pp. 268-273, 459-464.
Microsoft (2000). SQL Server Books Online. Creating and
Maintaining Databases – Views. SQL Server 2000 Enterprise
Manager – Help File.
Riordan, R. M. (2001). Microsoft SQL Server 2000 Programming
Step by Step. Microsoft Press. Redmond, WA. 1st Ed. Pp. 299322.