PL-900 Demonstrate the capabilities of Power Apps Practice Question
An organization uses a Canvas app to capture customer feedback. The app writes data to a Dataverse table. Recently, users have been submitting duplicate records due to double-clicking the submit button. What is the best way to prevent duplicates?
⚠ Common exam trap
PL-900 often tests the confusion between preventing duplicates at the UI layer (DisplayMode) versus detecting them after the fact (business rules or flows), and candidates wrongly pick reactive cleanup over proactive prevention.
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
✓
Disable the submit button after the first click using the DisplayMode property
Setting the submit button's DisplayMode property to Disabled after the first click prevents the user from triggering the OnSelect logic a second time, which directly stops duplicate records at the source. This is the standard Power Apps pattern for idempotent form submission because it blocks the second event before it can create another Dataverse row.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Set the form to require a unique ID before submission
Why it's wrong here
Requiring a unique ID does not stop the double-click; the second submission simply carries a different generated value, so two records persist. It is tempting because uniqueness feels like duplicate prevention, and would be correct for enforcing data integrity on imported records rather than blocking rapid resubmission.
- ✓
Disable the submit button after the first click using the DisplayMode property
Why this is correct
Setting the button's DisplayMode to Disabled after submission blocks further clicks, so the OnSelect patch runs once and duplicate Dataverse records are prevented. This directly addresses the double-click cause rather than filtering duplicates after they are created.
- ✗
Add a business rule to check for duplicates before saving
Why it's wrong here
Business rules run on Dataverse table save events, not on the Canvas app's button click, so a rapid double-click can still trigger two submissions before either rule evaluates. Business rules suit enforcing field validation and cross-column logic on forms, not throttling client-side submit actions.
- ✗
Use a Power Automate flow to delete duplicates after creation
Why it's wrong here
A flow deleting duplicates runs after both records are committed, so duplicates still appear and may already have triggered downstream notifications or reports. Post-creation cleanup suits reconciling legacy or imported data, not preventing duplicates caused by rapid double-clicking at submission time.
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Microsoft exam blueprint
This PL-900 practice question is part of Courseiva's free Microsoft certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the PL-900 exam.