Imports stage external data and transform it into target records. Matching rules determine whether records are created or updated.
Before you start
You should understand tables, records and the difference between client-side and server-side scripts. Work in a development instance with representative permissions. Identify execution scope, transaction timing and the current user before attributing behavior to a platform script or business rule.
The practical goal is to reason through this situation: A stable external identifier can support consistent matching across repeated imports. Read the walkthrough first, then try the interview exercise before opening its answer. The important part is explaining the decision and its consequences, rather than remembering a definition alone.
Step-by-step walkthrough
Step 1: Choose stable matching keys
External identity should remain stable across repeat imports.
Step 2: Validate transformation
Reject or route malformed records without guessing their target.
Step 3: Test create versus update
Coalescing rules determine whether repeated input changes existing records.
Worked scenario
A stable external identifier can support consistent matching across repeated imports.
An import matches users by display name. Renaming a user creates another record, while duplicate names can overwrite the wrong user. A stable source-specific identifier gives matching a deliberate meaning; missing or duplicate external keys still require a rejection or reconciliation policy.
Common mistake
Matching by a changing display name can create duplicates or overwrite unrelated records.
Verify the behavior
Repeat the import and test renamed, duplicate-key and missing-key records.
Interview exercise
Design a repeatable import.
Answer and reasoning
Validate keys and mappings, define coalescing behavior and test duplicate, missing and malformed inputs.
Continue learning
Compare the scenario with the ServiceNow interview questions and test your understanding with the ServiceNow MCQs. For terminology and implementation details, consult the reference material.