SF-Data-Arch Data Modeling and Database Design Practice Question
Which field type should be used for a primary key when integrating data from an external ERP system into Salesforce?
⚠ Common exam trap
Candidates frequently confuse standard ID fields with External ID fields, failing to realize that native Salesforce IDs are system-generated and cannot be used for external system integration mapping.
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
✓
External ID field
External IDs are critical for data integration. By marking a field as an External ID and setting it to Unique, Salesforce enables the 'Upsert' operation. This prevents duplicate records by matching the external system's primary key to the Salesforce record, ensuring data consistency across disparate platforms. This is the standard best practice for any integration involving master data management or synchronization between external systems and Salesforce.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
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Text field
Why it's wrong here
A standard text field does not have the 'External ID' attribute. Without this, you cannot perform an Upsert operation, meaning you would have to manually query for existing records to decide whether to update or insert, which is inefficient and prone to race condition errors.
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Auto-number field
Why it's wrong here
Auto-number fields are generated by Salesforce and cannot be mapped to an external primary key. They are internal identifiers and are useless for syncing with an external ERP, as the external system would have its own keying strategy that would not align with Salesforce's internal generation.
- ✓
External ID field
Why this is correct
An External ID field, marked as unique, is designed specifically for this integration use case. It allows the Upsert operation to identify existing records based on the ERP key, ensuring that data is updated correctly rather than creating duplicate entries during every data synchronization cycle.
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Formula field
Why it's wrong here
Formula fields are read-only and cannot be used as an External ID. They are calculated at runtime and do not store data in the database in a way that allows for matching or indexing, making them completely unsuitable for use as a primary key for integration purposes.
About these practice questions
This SF-Data-Arch question is part of Courseiva's 222-question bank — original exam-style content with full explanations and wrong-answer analysis, never real exam questions or exam dumps. Learn why practice questions differ from exam dumps →
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 Salesforce exam blueprint
This SF-Data-Arch practice question is part of Courseiva's free Salesforce 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 SF-Data-Arch exam.