DA0-002 Data Acquisition and Preparation Practice Question
A retail company is integrating sales data from three regional databases into a central data warehouse. The 'product_id' column is defined as an integer in two databases but as a variable-length string in the third. During the ETL process, the analyst must ensure that product_id values are consistent for joining with the product dimension table. Which data transformation should the analyst perform?
⚠ Common exam trap
The trap here is assuming that numeric identifiers should always be stored as integers, ignoring the possibility of alphanumeric or leading-zero values.
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
✓
Convert all product_id values to string
The product_id column must have a consistent data type across all sources to perform joins. Converting all values to string is the safest choice because it preserves leading zeros and any alphanumeric characters. Integer conversion could fail or lose information if the string column contains non-numeric values. String conversion ensures compatibility without data loss.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Apply data normalization to product_id
Why it's wrong here
Normalization typically scales numeric values or organizes tables to reduce redundancy. Applying it to product_id would not resolve the data type mismatch and could alter the values in unintended ways. Normalization is not a data type harmonization technique.
- ✓
Convert all product_id values to string
Why this is correct
Converting all product_id values to a string data type ensures consistency and avoids loss of leading zeros or non-numeric characters. String representation is the most flexible for joining across sources, as it accommodates numeric and alphanumeric identifiers. This transformation aligns the data types for the join operation.
- ✗
Convert all product_id values to integer
Why it's wrong here
Converting all product_id values to integer assumes that the string-based product_id contains only numeric characters and no leading zeros or non-numeric codes. If the string column includes alphanumeric identifiers, conversion would fail or lose information. This approach is risky without validating the data first.
- ✗
Use data aggregation on product_id
Why it's wrong here
Aggregation summarizes multiple rows into a single value, such as counting or summing. Product_id is an identifier and should not be aggregated because that would collapse distinct products. Aggregation would not address the type inconsistency and would corrupt the data for joining.
Go deeper
Related to this question
About these practice questions
This DA0-002 question is part of Courseiva's 1,004-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 CompTIA exam blueprint
This DA0-002 practice question is part of Courseiva's free CompTIA 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 DA0-002 exam.