Adobe Dreamweaver CC 2014 v.13 - Manual (Page 654)

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receives a request for a dynamic page, however, it reacts differently: It passes the page to a special piece of software responsible for finishing the
page. This special software is called an application server.
The application server reads the code on the page, finishes the page according to the instructions in the code, and then removes the code from
the page. The result is a static page that the application server passes back to the web server, which then sends the page to the requesting
browser. All the browser gets when the page arrives is pure HTML. Here’s a view of the process:
1. Web browser requests dynamic page. 2. Web server finds page and passes it to application server. 3. Application server scans page for
instructions and finishes page. 4. Application server passes finished page back to web server 5. Web server sends finished page to requesting
browser
Accessing a database
An application server lets you work with server-side resources such as databases. For example, a dynamic page may instruct the application
server to extract data from a database and insert it into the page’s HTML. For more information, see
www.adobe.com/go/learn_dw_dbguide .
Using a database to store content allows you to separate your website’s design from the content you want to display to site users. Instead of
writing individual HTML files for every page, you only need to write a page—or template—for the different kinds of information you want to present.
You can then upload content into a database and then have the website retrieve that content in response to a user request. You can also update
information in a single source, and then populate that change throughout the website without having to manually edit each page. You can use
Adobe® Dreamweaver® to design web forms to insert, update, or delete data from the database.
The instruction to extract data from a database is called a database query. A query consists of search criteria expressed in a database language
called SQL (Structured Query Language). The SQL query is written into the page’s server-side scripts or tags.
An application server cannot communicate directly with a database because the database’s proprietary format renders the data undecipherable in
much the same way that a Microsoft Word document opened in Notepad or BBEdit may be undecipherable. The application server can
communicate with the database only through the intermediary of a database driver: software that acts like an interpreter between the application
server and the database.
After the driver establishes communication, the query is executed against the database and a recordset is created. A recordset is a set of data
extracted from one or more tables in a database. The recordset is returned to the application server, which uses the data to complete the page.
Here’s a simple database query written in SQL:
SELECT lastname, firstname, fitpoints
FROM employees
This statement creates a three-column recordset and fills it with rows containing the last name, first name, and fitness points of all employees in
the database. For more information, see
www.adobe.com/go/learn_dw_sqlprimer .
The following example shows the process of querying a database and returning data to the browser:
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