---
id: sql-and
title: "SQL And"
category: "Database"
status: "draft"
verification_status: "conceptual"
canonical_id: ""
aliases: ["SQL AND Operator", "AND operator", "SQL 논리곱"]
duplicate_of: ""
source_trust_level: "B"
confidence_score: 0.9
created_at: 2026-07-04
updated_at: 2026-07-04
review_reason: ""
merge_history: []
tags: ["sql", "database", "w3schools", "and", "operators", "where"]
raw_sources: ["https://www.w3schools.com/sql/sql_and.asp"]
applied_in: []
github_commit: ""
---

# [[SQL And]]

## 🎯 한 줄 통찰 (One-line insight)
The AND operator filters records so that a row is returned only when ALL chained conditions in the WHERE clause are true. [S1]

## 🧠 핵심 개념 (Core concepts)
- **AND operator** — combines multiple conditions in a WHERE clause; a record is returned only if every condition is TRUE. [S1]
- **Syntax** — `SELECT ... FROM table_name WHERE condition1 AND condition2 AND condition3 ...;`. [S1]
- **AND vs. OR** — AND requires all conditions true; OR requires at least one condition true. [S1]
- **Combining AND and OR** — parentheses control evaluation grouping when mixing the two operators. [S1]

## 🧩 추출된 패턴 (Extracted patterns)
- **Parenthesize when mixing AND/OR** — `WHERE Country = 'Spain' AND (CustomerName LIKE 'G%' OR CustomerName LIKE 'R%')` gives the intended grouped result; omitting the parentheses changes which rows match because AND/OR precedence is not what the un-parenthesized reading suggests. [S1]

## ⚖️ 비교 및 선택 기준 (Comparison & decision criteria)

| 항목 (Option) | 장점 | 단점 | 언제 선택 |
|---|---|---|---|
| **괄호로 그룹화** | 의도한 대로 정확한 결과, 가독성 향상 | 코드가 약간 길어짐 | AND/OR를 섞어 쓸 때 항상 |
| **괄호 생략** | 짧음 | 연산자 우선순위로 인해 의도와 다른 결과가 나올 위험 | 단일 연산자만 사용할 때 |

## 📖 세부 내용 (Details)
- Filter on two conditions: `SELECT * FROM Customers WHERE Country = 'Spain' AND CustomerName LIKE 'G%';`. [S1]
- Filter on three conditions: `WHERE Country = 'Brazil' AND City = 'Rio de Janeiro' AND CustomerID > 50;`. [S1]
- Mixed AND/OR, correctly grouped with parentheses: `WHERE Country = 'Spain' AND (CustomerName LIKE 'G%' OR CustomerName LIKE 'R%');` — without the parentheses, the same text returns a different (wider) result set, since it becomes "Spain AND starts-with-G" OR "starts-with-R regardless of country". [S1]

## ⚖️ 모순 및 업데이트 (Contradictions & updates)
소스에서 모순되는 정보는 발견되지 않음. 다만 괄호 유무에 따라 동일해 보이는 조건식이 다른 결과를 낼 수 있다는 점이 소스 내에서 직접 경고됨. [S1]

## 🛠️ 적용 사례 (Applied in summary)
현재 발견된 실제 적용 사례가 없습니다 — WHERE 절 다중 조건 필터링에서 OR/NOT과 함께 가장 빈번히 재사용되는 연산자다. [S1]

## 💻 코드 패턴 (Code patterns)
Multiple AND conditions (SQL):
```sql
SELECT * FROM Customers
WHERE Country = 'Brazil'
AND City = 'Rio de Janeiro'
AND CustomerID > 50;
```
Correctly grouped AND + OR (SQL):
```sql
SELECT * FROM Customers
WHERE Country = 'Spain' AND (CustomerName LIKE 'G%' OR CustomerName LIKE 'R%');
```

## ✅ 검증 상태 및 신뢰도
- **상태:** draft
- **검증 단계:** conceptual
- **출처 신뢰도:** B (W3Schools — widely used educational reference, not a primary standards body)
- **신뢰 점수:** 0.90
- **중복 검사 결과:** 신규 생성 (New discovery)

## 🔗 지식 그래프 (Knowledge Graph)
- **상위/루트:** [[SQL Tutorial]]
- **관련 개념:** [[SQL Where]], [[SQL Or]], [[SQL Not]]
- **참조 맥락:** WHERE 절 다중 조건 결합의 기본 연산자 — OR/NOT과 세트로 이해해야 한다.

## 📚 출처 (Sources)
- [S1] W3Schools — SQL AND Operator — https://www.w3schools.com/sql/sql_and.asp

## 📝 변경 이력 (Change history)
- 2026-07-04: Initial draft synthesized from the W3Schools "SQL AND Operator" page (Astra wiki-curation, P-Reinforce v3.1 format).