EC-Council
312-50V10 · Question #342
312-50V10 Question #342: Real Exam Question with Answer & Explanation
The correct answer is A: --. In SQL, a double hyphen (--) begins a single-line comment, causing the database engine to ignore everything after it on that line.
Question
Which of the following is used to indicate a single-line comment in structured query language (SQL)?
Options
- A--
- B||
- C%%
- D''
Explanation
In SQL, a double hyphen (--) begins a single-line comment, causing the database engine to ignore everything after it on that line.
Common mistakes.
- B. || is the standard SQL string concatenation operator (used in Oracle, PostgreSQL, and ANSI SQL) and has no comment-related function.
- C. %% is not valid SQL syntax; a single % is used as a wildcard character within LIKE predicate patterns, not for comments.
- D. '' represents an empty string literal in SQL and has no comment functionality.
Concept tested. SQL single-line comment syntax and injection
Reference. https://learn.microsoft.com/en-us/sql/t-sql/language-elements/comment-transact-sql
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