Question 340 of 986
DA0-002 Data Acquisition and Preparation Practice Question
A data analyst is merging two datasets from different departments. The analyst notices that the 'CustomerID' field in the first dataset is stored as an integer, while in the second dataset it is stored as a string with leading zeros. Which TWO steps should the analyst take to ensure successful data integration?
⚠ Common exam trap
Watch out — candidates often assume implicit type conversion will handle the join correctly, but they overlook that leading zeros are lost during conversion, causing silent data loss or incorrect matches.
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
✓
Use a left join and treat the CustomerID as a string after conversion.
Converting the integer CustomerID to a string ensures both datasets have a compatible data type for the join. This approach preserves the leading zeros in the second dataset, which are semantically significant (e.g., '00123' vs. 123). A left join is appropriate to retain all records from the primary dataset while matching on the converted key.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Perform the merge directly without transformation since databases handle type conversions automatically.
Why it's wrong here
Automatic conversion may not preserve leading zeros and could cause errors.
- ✗
Strip all non-numeric characters from the string CustomerID before joining.
Why it's wrong here
This could alter IDs that contain letters or symbols.
- ✓
Use a left join and treat the CustomerID as a string after conversion.
Why this is correct
A left join requires matching keys; converting to string ensures compatibility.
- ✗
Convert the string CustomerID to an integer by removing leading zeros.
Why it's wrong here
This would lose the leading zeros, potentially causing mismatches.
- ✓
Convert the integer CustomerID to a string with leading zeros to match the format in the second dataset.
Why this is correct
This ensures both CustomerID fields have the same data type and format.
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Last reviewed: Jun 11, 2026
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.
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