DA0-002 Data Acquisition and Preparation Practice Question
A data analyst needs to create a new column 'full_name' by concatenating 'first_name' and 'last_name' with a space. Which SQL function should be used in the SELECT clause?
⚠ Common exam trap
The trap is the '+' operator, which looks intuitive for concatenation but is dialect-specific and often performs numeric addition instead — the exam expects the portable CONCAT() answer.
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
✓
CONCAT(first_name, ' ', last_name)
CONCAT(first_name, ' ', last_name) is the standard SQL function for joining strings, and it correctly inserts a literal space between the two columns. CONCAT accepts multiple arguments and returns a single concatenated string, which can be aliased as full_name in the SELECT clause.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
COMBINE(first_name, last_name)
Why it's wrong here
COMBINE is not a SQL function in any major dialect, so the statement fails to parse. It is tempting because its name describes the intended operation, but the actual concatenation function is CONCAT, which accepts the two columns and a space literal.
- ✓
CONCAT(first_name, ' ', last_name)
Why this is correct
CONCAT accepts multiple arguments and returns their concatenation, so it joins first_name, a literal space and last_name into one string within the SELECT clause. The space must be supplied explicitly as a separate argument, since CONCAT does not insert separators between values.
- ✗
JOIN(first_name, last_name)
Why it's wrong here
JOIN is a relational operator that combines rows from two tables, not a scalar function for merging column values within a row. It is tempting because the word suggests combining, but it operates on tables in the FROM clause, not on strings in SELECT.
- ✗
first_name + ' ' + last_name
Why it's wrong here
The + operator performs numeric addition in most SQL dialects and will error or coerce names, rather than concatenating strings. It is tempting because + concatenates in SQL Server and some others, but the portable, standard function for joining text with a separator is CONCAT (or the || operator), which handles the space correctly.
About these practice questions
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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.