hardMultiple Select
FC0-U71 Practice Question: Which TWO of the following are common causes of…
Which TWO of the following are common causes of errors when executing a SELECT query? (Choose two.)
⚠ Common exam trap
Many candidates confuse performance issues (large table, missing index, slow network) with actual query execution errors, but only syntax or schema mismatches (incorrect column name, missing table name) cause the query to fail.
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
✓
Incorrect column name
Option B (Incorrect column name) is correct because a SELECT statement referencing a column that does not exist in the target table will fail with an error such as 'Unknown column' in MySQL or 'Invalid column name' in SQL Server, since the parser cannot resolve the identifier against the table's schema. Option D (Missing table name) is correct because a SELECT query must specify a FROM clause with a valid table (or equivalent source); omitting it or naming a nonexistent table produces errors like 'No tables used' or 'Table doesn't exist'. Option A (Table is too large) is not a cause of query errors—large tables may affect performance, but the query still executes correctly. Option C (Index is missing) is not an error cause either; a missing index only slows execution, and the query returns correct results via a full scan. Option E (Network is slow) is unrelated to query correctness—it may cause timeouts or latency but does not itself make a SELECT statement erroneous.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Table is too large
Why it's wrong here
A large table slows retrieval but does not itself produce an error; the statement remains valid. It is tempting because size correlates with poor performance, and it would be correct when capacity or query-timeout tuning is the concern rather than a malformed or unresolvable SELECT.
- ✓
Incorrect column name
Why this is correct
An incorrect column name causes the database engine to fail parsing, returning an "invalid column name" error before execution. This satisfies the stem's requirement for a common SELECT error, since the query references a column absent from the target table or view, breaking name resolution during compilation.
- ✗
Index is missing
Why it's wrong here
A missing index causes slow scans, not an error; the query still returns correct rows. It is tempting because indexing is a common tuning topic, and it would be correct when optimising a valid query's performance rather than explaining why execution fails.
- ✓
Missing table name
Why this is correct
Omitting the table name from the FROM clause leaves the query with no data source, so the database engine cannot resolve which columns to read and returns a syntax or binding error. This directly satisfies the stem's requirement by naming a genuine, common cause of SELECT execution failure.
- ✗
Network is slow
Why it's wrong here
Slow network affects query latency, not the validity of the SQL statement, so it produces no execution error. It is tempting because performance degradation feels like failure, and it would be correct when diagnosing timeouts on a remote database connection rather than syntax or schema faults.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This FC0-U71 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 FC0-U71 exam.