---
id: sql-full-join
title: "SQL Full Join"
category: "Database"
status: "draft"
verification_status: "conceptual"
canonical_id: ""
aliases: ["FULL JOIN", "FULL OUTER JOIN", "SQL 전체 외부 조인"]
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", "join", "full-join"]
raw_sources: ["https://www.w3schools.com/sql/sql_join_full.asp"]
applied_in: []
github_commit: ""
---

# [[SQL Full Join]]

## 🎯 한 줄 통찰 (One-line insight)
FULL JOIN unions the behavior of LEFT and RIGHT JOIN — it keeps every row from both tables, filling NULL wherever the other side has no match, and can return very large result sets. [S1]

## 🧠 핵심 개념 (Core concepts)
- **FULL JOIN** — returns all rows when there is a match in either the left or right table. [S1]
- **NULL-filling both sides** — an unmatched left row gets NULLs for all right-table columns, and vice versa. [S1]
- **FULL JOIN == FULL OUTER JOIN** — the `OUTER` keyword is optional. [S1]
- **Syntax** — `SELECT column_name(s) FROM table1 FULL JOIN table2 ON table1.column_name = table2.column_name WHERE condition;`. [S1]

## 🧩 추출된 패턴 (Extracted patterns)
- **Size warning** — the source explicitly warns "FULL JOIN can potentially return very large result-sets!", making it something to use deliberately rather than by default. [S1]

## 📖 세부 내용 (Details)
- All customers and all orders together, whether or not they match: `SELECT Customers.CustomerName, Orders.OrderID FROM Customers FULL JOIN Orders ON Customers.CustomerID = Orders.CustomerID;`. [S1]
- Result includes rows with `CustomerName = Null` (orders with no matching customer) and rows with `OrderID = Null` (customers with no orders). [S1]

## ⚖️ 모순 및 업데이트 (Contradictions & updates)
소스에서 모순되는 정보는 발견되지 않음.

## 🛠️ 적용 사례 (Applied in summary)
현재 발견된 실제 적용 사례가 없습니다 — 데이터 정합성 점검(양쪽 테이블 모두에서 누락된 레코드 찾기)에 전형적으로 쓰이는 조인 유형이다. [S1]

## 💻 코드 패턴 (Code patterns)
Full outer join (SQL):
```sql
SELECT Customers.CustomerName, Orders.OrderID
FROM Customers
FULL JOIN Orders
ON Customers.CustomerID = Orders.CustomerID;
```

## ✅ 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 Joins]], [[SQL Left Join]], [[SQL Right Join]]
- **참조 맥락:** 양쪽 테이블의 unmatched 행을 모두 보존해야 하는 데이터 정합성 점검 쿼리.

## 📚 출처 (Sources)
- [S1] W3Schools — SQL FULL JOIN — https://www.w3schools.com/sql/sql_join_full.asp

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