--- id: sql-right-join title: "SQL Right Join" category: "Database" status: "draft" verification_status: "conceptual" canonical_id: "" aliases: ["RIGHT JOIN", "RIGHT OUTER JOIN", "SQL 오른쪽 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", "right-join"] raw_sources: ["https://www.w3schools.com/sql/sql_join_right.asp"] applied_in: [] github_commit: "" --- # [[SQL Right Join]] ## 🎯 한 줄 통찰 (One-line insight) RIGHT JOIN is LEFT JOIN with the table roles mirrored — it keeps every row from the right table regardless of a match, filling unmatched left-table columns with NULL. [S1] ## 🧠 핵심 개념 (Core concepts) - **RIGHT JOIN** — returns all rows from the right table (table2), and only the matched rows from the left table (table1); unmatched left-side columns become NULL. [S1] - **RIGHT JOIN == RIGHT OUTER JOIN** — the `OUTER` keyword is optional. [S1] - **Syntax** — `SELECT column_name(s) FROM table1 RIGHT JOIN table2 ON table1.column_name = table2.column_name;`. [S1] ## 🧩 추출된 패턴 (Extracted patterns) - **LEFT/RIGHT symmetry** — a RIGHT JOIN can always be rewritten as a LEFT JOIN by swapping which table is written first; teams often standardize on LEFT JOIN alone for consistency (implied by RIGHT JOIN's comparative rarity in practice, though not stated verbatim in the source). [S1] ## 📖 세부 내용 (Details) - All employees and any orders they placed (employees preserved even with zero orders): `SELECT Orders.OrderID, Employees.LastName, Employees.FirstName FROM Orders RIGHT JOIN Employees ON Orders.EmployeeID = Employees.EmployeeID ORDER BY Orders.OrderID;`. [S1] - The RIGHT JOIN keyword returns all records from the right table (Employees), even where there is no match in the left table (Orders). [S1] ## ⚖️ 모순 및 업데이트 (Contradictions & updates) 소스에서 모순되는 정보는 발견되지 않음. ## 🛠️ 적용 사례 (Applied in summary) 현재 발견된 실제 적용 사례가 없습니다 — "직원별 주문 실적(0건 포함)" 같은 리포트에서 전형적으로 쓰이는 패턴이다. [S1] ## 💻 코드 패턴 (Code patterns) All rows from right table (SQL): ```sql SELECT Orders.OrderID, Employees.LastName, Employees.FirstName FROM Orders RIGHT JOIN Employees ON Orders.EmployeeID = Employees.EmployeeID ORDER BY Orders.OrderID; ``` ## ✅ 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 Full Join]] - **참조 맥락:** LEFT JOIN의 대칭 개념 — 오른쪽 테이블의 모든 행을 보존해야 할 때 사용. ## 📚 출처 (Sources) - [S1] W3Schools — SQL RIGHT JOIN — https://www.w3schools.com/sql/sql_join_right.asp ## 📝 변경 이력 (Change history) - 2026-07-04: Initial draft synthesized from the W3Schools "SQL RIGHT JOIN" page (Astra wiki-curation, P-Reinforce v3.1 format).