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Oracle JHeadstart Developer's Guide - Downloads - Oracle

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5.6.3. Variation: Recursive Tree<br />

• Change the Layout Style property to 'tree' for the groups Regions and<br />

Countries2.<br />

Attention: The value of the Data Collection (the "tree select usage") property<br />

is not used with this layout style, because this tree level cannot be edited. It<br />

does not matter which usage you specify, but you must specify one because it<br />

is a required property.<br />

• Regenerate. You will get something like this:<br />

Notice the absence of links on the REGIONS ('Americas') and COUNTRIES ('US') level.<br />

In some cases, tree structures are modeled in the database with self-referencing foreign<br />

keys (visible in Entity-Relationship diagrams by the so-called pig's ear).<br />

Example: Employees have a manager. The manager is also an employee, so this is<br />

modeled as a foreign key from EMPLOYEES to EMPLOYEES.<br />

5 - 30 Generating Page Layouts <strong>JHeadstart</strong> Developer’s <strong>Guide</strong>

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