Page 306 - DCAP408_WEB_PROGRAMMING

Web Programming

Notes 14.2 Reading Records from Database

Databases and ASP (Communicating with a Database using ActiveX Data Objects (ADO);
Connecting to a Database (The Connection Object, Using a System DSN, Using a DSN-less
Connection, Opening the Connection, Closing the connection, Properties of the connection);
Reading data from a Database (The Recordset Object, Using adovbs.inc, Reading and Displaying
the contents of a Database Table).
Internet programming is one of the most exciting new fields to develop in recent years, and will
continue growing in importance, especially for Visual Basic programmers. In response, Microsoft
is pushing hard to integrate several of its key technologies, in order to allow developers to create
Internet solutions that scale well and that are quick to develop. Server-side technologies are where
the new advances in Internet technology will likely be made – at least in the near future, which is
about as far as we can ever see in today’s rapidly changing technological landscape.
Active Server Pages (ASP) is a server-side technology that accomplishes this very feat: an ASP
script is a combination of HTML and ASP objects that work together to produce a pure HTML
file. The client never sees the script, which resides on the server, they just see the output. ASP is
basically a collection of objects that handle all aspects of a Web site, from communicating with
the client, to managing multiple connections. ASP is firmly grounded in Visual Basic
programming concepts. In fact, Visual Basic is rapidly emerging as a premier language for
developing Web solutions, as you will appreciate by the end of this article. My concern here is
a DSN-less connection.
A DSN-less connection is operationally identical to a DSN except that the server doesn’t have to
access the registry to access the parameters since they’re all specified in the connection string itself.

Did u know? Which parameter is required by ODBC connection?

The only parameter required by all ODBC connection strings is Driver which specifies
which driver to use. Unfortunately this isn’t enough to get connected to anything and
additional information is required by each driver.
Now we will see how we read a database using ASP(communicating with a database Active X
Data Objects(ADO),connecting to a database using a DSN-less connection, its opening ,closing,
properties &of course reading the data, displaying it using adovbs.inc.

14.2.1 Reading Records with ADO

Recordset Object

The recordset object provides a relatively simple interface o read records from a database.
ADO was introduced and thrived in a time-frame when connected and (mostly) two-tier
applications were moving to a more layered and Web-based architecture. The overall ADO
object model design reflects this transition.
The Web forced the adoption of a disconnected model where more and more information is
downloaded and cached on the client. Within ADO, you find two souls hidden just under the
skin of the Recordset object.

The Recordset can leverage server cursors and do what it is supposed to do being connected to
the data source all the time. At the same time, another facet of the same object can work
disconnected and build up a correct representation of records in two ways. Either it can fetch

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