SNOW-CAD Practice Question: Automating application logic with business rules and scripts
A developer writes a Business Rule to calculate a total on an Aggregate field. The rule runs on 'insert' and 'update' on the parent table. However, the total is not updating correctly when child records are deleted. Why?
⚠ Common exam trap
Candidates often assume a Business Rule on the parent table with a 'delete' event will catch child deletions, but in ServiceNow, the delete event only fires on the table where the record is actually deleted, not on related parent records.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The Business Rule should be on the child table's delete event.
A Business Rule that runs on 'insert' and 'update' on the parent table will not fire when a child record is deleted, because the delete event occurs on the child table, not the parent. To correctly update an aggregate field on the parent when child records are deleted, the Business Rule must be defined on the child table's 'delete' event. This ensures the rule executes when the child record is removed, allowing the aggregate to be recalculated.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The Business Rule should use 'current' and 'previous' to detect deletion.
Why it's wrong here
Previous is not available in delete context.
- ✓
The Business Rule should be on the child table's delete event.
Why this is correct
Child delete triggers need separate rule on child table.
- ✗
The Business Rule should also run on 'delete'.
Why it's wrong here
Delete of parent not relevant.
- ✗
The Business Rule should be a Global Business Rule.
Why it's wrong here
Global rule does not solve trigger issue.
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