2nd/10_Wiki/Dev/Topic_SQL/SQL_Comments.md

id, title, category, status, verification_status, canonical_id, aliases, duplicate_of, source_trust_level, confidence_score, created_at, updated_at, review_reason, merge_history, tags, raw_sources, applied_in, github_commit

id	title	category	status	verification_status	canonical_id	aliases	duplicate_of	source_trust_level	confidence_score	created_at	updated_at	review_reason	merge_history	tags	raw_sources	applied_in	github_commit
sql-comments	SQL Comments	Database	draft	conceptual		SQL comment syntax SQL 주석		B	0.88	2026-07-04	2026-07-04			sql database w3schools comments	https://www.w3schools.com/sql/sql_comments.asp

SQL Comments

🎯 한 줄 통찰 (One-line insight)

SQL supports single-line (--) and multi-line (/* */) comments, ignored by the database engine, useful both for documentation and for temporarily disabling parts of a statement — except in Microsoft Access, which supports neither. [S1]

🧠 핵심 개념 (Core concepts)

• Purpose — explain SQL code, or temporarily prevent execution of code (for debugging); comments are ignored by the database engine. [S1]
• Single-line comments — start with -- and continue to the end of the line. [S1]
• Multi-line comments — start with /* and end with */; any text between is ignored. [S1]
• MS Access exception — comments are not supported in Microsoft Access databases. [S1]

🧩 추출된 패턴 (Extracted patterns)

• Comment-out-to-disable — appending -- or wrapping in /* */ is used not just for documentation but as a quick way to disable a clause, a whole statement, or several statements at once without deleting code. [S1]
• Inline partial comment — a multi-line comment can mask just part of a line/statement (e.g. commenting out one column or one OR-branch) while the rest still executes. [S1]

📖 세부 내용 (Details)

• Single-line as explanation: -- Selects all German customers followed by the query. [S1]
• Single-line to comment out the end of a line: SELECT * FROM Customers -- WHERE City='Berlin';. [S1]
• Single-line to disable an entire statement: -- SELECT * FROM Customers; followed by a different active statement. [S1]
• Multi-line as explanation: /* Selects all German customers from Berlin */ followed by the query. [S1]
• Multi-line to disable several statements at once. [S1]
• Multi-line to mask part of a column list: SELECT CustomerName, /*City,*/ Country FROM Customers;. [S1]
• Multi-line to mask part of an OR chain inside a WHERE clause. [S1]

⚖️ 모순 및 업데이트 (Contradictions & updates)

• MS Access는 주석을 지원하지 않음 — 다른 모든 SQL 방언과 다른 예외 사항으로 소스에 명시됨. [S1]

🛠️ 적용 사례 (Applied in summary)

현재 발견된 실제 적용 사례가 없습니다 — 디버깅 중 쿼리 일부를 임시로 비활성화하는 용도로 실무에서 흔히 쓰인다. [S1]

💻 코드 패턴 (Code patterns)

Single-line and multi-line comments (SQL):

-- Selects all German customers
SELECT * FROM Customers
WHERE Country = 'Germany';

/* Selects all German customers
   from Berlin */
SELECT * FROM Customers
WHERE Country = 'Germany' AND City = 'Berlin';

✅ 검증 상태 및 신뢰도

• 상태: draft
• 검증 단계: conceptual
• 출처 신뢰도: B (W3Schools — widely used educational reference, not a primary standards body)
• 신뢰 점수: 0.88
• 중복 검사 결과: 신규 생성 (New discovery)

🔗 지식 그래프 (Knowledge Graph)

• 상위/루트: SQL Tutorial
• 관련 개념: SQL Syntax
• 참조 맥락: SQL 코드 문서화 및 디버깅 시 쿼리 일부를 비활성화할 때 사용 — MS Access에서는 지원되지 않음에 유의.

📚 출처 (Sources)

• [S1] W3Schools — SQL Comments — https://www.w3schools.com/sql/sql_comments.asp

📝 변경 이력 (Change history)

• 2026-07-04: Initial draft synthesized from the W3Schools "SQL Comments" page (Astra wiki-curation, P-Reinforce v3.1 format).