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

# [[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):
```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).