DA0-002 Data Concepts and Environments Practice Question
A data analyst at a logistics company is designing a new database table to store shipment records. Each shipment has a unique tracking number, a weight in kilograms, a destination city, and a delivery date. The analyst needs to choose a data type for the tracking number that ensures uniqueness and efficient lookups. Which data type is most appropriate for the tracking number?
⚠ Common exam trap
The trap here is assuming that a numeric-looking identifier should be stored as an integer, which discards leading zeros and breaks alphanumeric formats.
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
✓
Character string
Tracking numbers are identifiers that may include letters, leading zeros, and varying lengths, so a character string data type preserves their exact format and supports unique constraints. Integer, Boolean, and date/time types each fail to represent the full range of possible tracking numbers, risking data loss or inability to enforce uniqueness. Character strings also allow efficient indexing for fast lookups.
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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Boolean
Why it's wrong here
Boolean data types store only true/false or 0/1 values, which cannot represent a tracking number with multiple digits or characters. Using Boolean would collapse all tracking information into a binary state, making it impossible to distinguish shipments. This type is suitable for flags like 'delivered' but completely fails to capture the unique identifier required for each shipment record.
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Integer
Why it's wrong here
Integer data types store whole numbers and are efficient for arithmetic, but tracking numbers often contain leading zeros or alphanumeric characters. Using an integer would strip leading zeros and fail for non-numeric tracking numbers. Additionally, integer storage does not inherently guarantee uniqueness; a separate constraint would still be required. For shipment tracking, integer is too restrictive and could cause data loss or lookup errors.
- ✗
Date/time
Why it's wrong here
Date/time data types store temporal values such as delivery date, not identifiers. While the table needs a delivery date column, using date/time for the tracking number would prevent storing alphanumeric codes and would not guarantee uniqueness. It also makes lookups by tracking number impossible because the value would be interpreted as a date, leading to errors and data corruption.
- ✓
Character string
Why this is correct
Character string (VARCHAR or CHAR) is ideal for tracking numbers because it preserves leading zeros, supports alphanumeric formats, and handles varying lengths. It ensures the exact identifier is stored without numeric conversion issues. Uniqueness can be enforced with a primary key or unique constraint. This data type also supports efficient indexing for lookups, making it the most appropriate choice for shipment tracking numbers.
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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
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