The AppML Database Element

With AppML, the <database> element defines a database connection.

The Database Element

AppML uses an <appml> document to describe an AppML application. Inside the AppML document a <database> element describes the connection to a database:

<appml>

<database>
<connection>music_db</connection>
<sql>select title,artist,year from cd_catalog</sql>
</database>

</appml>

A "view" of the database content is displayed below:

Database Sub Elements

The following sub elements can be used to add more information to the application:

• connection
• maintable
• keyfield
• sql

The Connection Element

The AppML <connection> element defines the name of a database connection.

AppML does not define how to connect to the database. It is up to the actual Web Service to do a proper connection. 

The Maintable Element

The AppML <maintable> element defines a database table.

The <maintable> element is used to define the main table of a database connection. Used together with the <keyfield> element, it defines how to update a database.

AppML also uses the <maintable> element to define a default sql statement if the <sql> element is omitted. 

This AppML description:

<appml>

<database>
  <connection>music_db</connection>
  <maintable>cd_catalog</maintable>
</database>

</appml>

Will default to this:

<appml>

<database>
  <connection>music_db</connection>
  <maintable>cd_catalog</maintable>
  <sql>select * from cd_catalog</sql>
</database>

</appml>

The Keyfield Element

The AppML <keyfield> element defines the primary key of a database table.

The <keyfield> can be used by a Web Service to define how to update a database.

The SQL Element

The <sql> element is used to define a subset of records from a database.

Most Web Services will use the <sql> element to extract data from a database. The content of the <sql> element can be any legal SQL statement. 

An XML Schema for AppML

If you have Internet Explorer, you can Click Here to view the full XML Schema for an AppML document.

Jump to: Top of Page or HOME or Printer friendly page

Search W3Schools:

What Others Say About Us

Does the world know about us? Check out these places:

Dogpile Alta Vista MSN Google Excite Lycos Yahoo Ask Jeeves

We Help You For Free. You Can Help Us!

• Tell your newsgroup or mailing list
• Link to us from your pages
• Help us correct errors and broken links
• Help us with spelling and grammar
• Validate the XHTML code of this page

W3Schools is for training only. We do not warrant its correctness or its fitness for use. The risk of using it remains entirely with the user. While using this site, you agree to have read and accepted our terms of use and privacy policy.

Copyright 1999-2002 by Refsnes Data. All Rights Reserved

How we converted to XHTML