This document discusses how to control data block relationships in Oracle Forms. It describes how to coordinate data blocks using REF relations, the characteristics of relation-handling triggers and code, and how to implement coordination-type toggling and force one commit per master record. Key aspects covered include defining relation properties, the clear and populate phases of block coordination, system variables for relation handling information, and procedures for toggling coordination type and enforcing a single commit.

1. Controlling Data Block Relationships
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2. Objectives
• Define block coordination
• Coordinate data blocks by using REF relations
• Describe the characteristics and
principles of relation-handling code
• System Variables for obtaining relation handling information
• Implement a coordination-type toggle
• Force one commit per master record
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3. Relations
• Logical objects that handle the relationship between two blocks
• Created implicitly with a master-detail form module
• Created explicitly with the New Relation dialog box
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4. Block Coordination
• Coordination-causing event
• Block-coordination phases:
– Clear phase executed before change
of master record
– Populate phase executed after
change of master record
• Implementation of block coordination:
– The Copy Value from Item property
– Relation-handling triggers
– Relation-handling procedures
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5. Creating REF Relationships
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6. Characteristics of Relation-Handling Triggers
• On-Clear-Details: Implements the Clear phase
• On-Populate-Details: Implements the
Populate phase
• On-Check-Delete-Master: Implements the restricted-delete rule
• Effect of trigger failure
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7. Principles of Relation-Handling Code
Three relation-handling procedures:
• CLEAR_ALL_MASTER_DETAILS
• QUERY_MASTER_DETAILS
• CHECK_PACKAGE_FAILURE
Adding your own code to relation-handling triggers:
• Forms adds comments around code.
• You add your own code before or after
these comments.
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8. Obtaining Relation-Handling Information
System variables for relation handling:
• SYSTEM.MASTER_BLOCK
• SYSTEM.COORDINATION_OPERATION
Built-ins for relation handling:
• GET_FORM_PROPERTY
• GET/SET_BLOCK_PROPERTY
• GET/SET _RELATION_PROPERTY
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9. Implementing Coordination-Type Toggle
Define a procedure that toggles between
immediate and deferred coordination
• Use GET_BLOCK_PROPERTY to obtain
relation name.
• Use GET_RELATION_PROPERTY to
obtain current coordination type.
• Use SET_RELATION_PROPERTY to
switch to other coordination type.
Call this procedure from:
• When-Checkbox-Changed trigger
• Menu item of type Check
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10. Forcing a Commit Per Master
Define a procedure that:
• Updates the commit status by
performing validation
• Checks the commit status of the master record
• Raises FORM_TRIGGER_FAILURE in
case of changes
Call the procedure:
• In the On-Clear-Details trigger
• Before the “Begin default relation
program section” comment
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11. Summary
• Define Relation coordination properties
• Manage data block coordination
– Coordination-causing events change
the master record
– Clear and populate
• System Variables for obtaining relation handling
information
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