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FC0-U71 Practice Question: Which TWO of the following are valid SQL…
Which TWO of the following are valid SQL functions used to aggregate data?
⚠ Common exam trap
It's easy for candidates to confuse SQL clauses (like ORDER BY for sorting) or scalar functions (like LENGTH) with aggregate functions, because they see them used in queries but fail to recognize the fundamental difference between row-level operations and set-level summarization.
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
✓
COUNT
COUNT (option A) is a valid SQL aggregate function that returns the number of rows or non-NULL values in a column, commonly used with GROUP BY to summarize data. SUM (option C) is also a valid SQL aggregate function that returns the total sum of a numeric column, making it a standard tool for data aggregation. The other options are not aggregate functions: SORT (option B) is not a SQL function (ordering is done with ORDER BY), LENGTH (option D) is a scalar string function that returns the character length of a value, and APPEND (option E) is not a standard SQL function at all.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
COUNT
Why this is correct
COUNT is an aggregate function that returns the number of rows or non-NULL values in a set, collapsing many rows into a single summary figure. It is used with GROUP BY or over an entire result set to produce totals.
- ✗
SORT
Why it's wrong here
SORT is not a SQL function at all; ordering result sets is achieved with the ORDER BY clause, which is a query modifier rather than an aggregate. It is tempting because sorting is a common data operation, and ORDER BY would be the correct construct when presenting aggregated results in a defined sequence.
- ✓
SUM
Why this is correct
SUM is a standard SQL aggregate function that returns the total of a numeric column across rows, collapsing many values into one. It satisfies the stem's requirement for a valid aggregation function, unlike scalar functions that operate row by row.
- ✗
LENGTH
Why it's wrong here
LENGTH returns the character count of a string, a scalar function operating per row, so it cannot collapse multiple rows into a single aggregated value. It is tempting because it appears alongside aggregate functions in SELECT lists, and would be correct for measuring string length within a row.
- ✗
APPEND
Why it's wrong here
APPEND is not a SQL aggregate function; adding rows is performed with the INSERT statement, which is DML rather than an aggregation operation. It is tempting because appending data is a routine database task, and INSERT would be the correct statement when adding new records to a table.
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