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79 lines
3.9 KiB
Markdown
79 lines
3.9 KiB
Markdown
---
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id: sql-views
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title: "SQL Views"
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category: "Database"
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status: "draft"
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verification_status: "conceptual"
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canonical_id: ""
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aliases: ["SQL CREATE VIEW Statement", "SQL View", "가상 테이블"]
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duplicate_of: ""
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source_trust_level: "B"
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confidence_score: 0.88
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created_at: 2026-07-04
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updated_at: 2026-07-04
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review_reason: ""
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merge_history: []
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tags: ["sql", "database", "w3schools", "view"]
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raw_sources: ["https://www.w3schools.com/sql/sql_view.asp"]
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applied_in: []
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github_commit: ""
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---
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# [[SQL Views]]
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## 🎯 한 줄 통찰 (One-line insight)
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A view is a virtual table backed only by a stored SELECT definition, not a data copy — so it always reflects real-time data, and updating it requires vendor-specific syntax (ALTER VIEW vs. CREATE OR REPLACE VIEW). [S1]
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## 🧠 핵심 개념 (Core concepts)
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- **SQL view** — a virtual table based on the result-set of an SQL statement; fields come from one or more real tables. [S1]
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- **Always real-time** — the database only stores the view's SELECT definition, not a data copy, so querying a view always reflects current data. [S1]
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- **Syntax (create)** — `CREATE VIEW view_name AS SELECT column1, column2, ... FROM table_name WHERE condition;`. [S1]
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- **Querying a view** — `SELECT * FROM view_name;`, exactly like querying a real table. [S1]
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- **Updating a view** — `ALTER VIEW` (SQL Server) vs. `CREATE OR REPLACE VIEW` (MySQL/Oracle). [S1]
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- **Dropping a view** — `DROP VIEW view_name;`. [S1]
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## 🧩 추출된 패턴 (Extracted patterns)
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- **View as a saved query with a table name** — a view can encapsulate a subquery-based filter (e.g. "products above average price") behind a simple table-like name, hiding the underlying complexity from downstream queries. [S1]
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## 📖 세부 내용 (Details)
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- Simple filtered view: `CREATE VIEW [Brazil Customers] AS SELECT CustomerName, ContactName FROM Customers WHERE Country = 'Brazil';`, queried as `SELECT * FROM [Brazil Customers];`. [S1]
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- View wrapping a subquery: `CREATE VIEW [Products Above Average Price] AS SELECT ProductName, Price FROM Products WHERE Price > (SELECT AVG(Price) FROM Products);`. [S1]
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- Update a view (SQL Server): `ALTER VIEW [Brazil Customers] AS SELECT CustomerName, ContactName, City FROM Customers WHERE Country = 'Brazil';`. [S1]
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- Update a view (MySQL/Oracle): `CREATE OR REPLACE VIEW [Brazil Customers] AS SELECT CustomerName, ContactName, City FROM Customers WHERE Country = 'Brazil';`. [S1]
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- Drop a view: `DROP VIEW [Brazil Customers];`. [S1]
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## ⚖️ 모순 및 업데이트 (Contradictions & updates)
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- **뷰 갱신 문법이 벤더별로 다름**: SQL Server는 `ALTER VIEW`, MySQL/Oracle은 `CREATE OR REPLACE VIEW`를 사용. [S1]
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## 🛠️ 적용 사례 (Applied in summary)
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현재 발견된 실제 적용 사례가 없습니다 — AVG() 서브쿼리를 뷰로 감싸 재사용 가능한 이름으로 노출하는 예시가 소스에 직접 등장한다. [S1]
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## 💻 코드 패턴 (Code patterns)
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Create and query a view (SQL):
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```sql
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CREATE VIEW [Brazil Customers] AS
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SELECT CustomerName, ContactName
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FROM Customers
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WHERE Country = 'Brazil';
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SELECT * FROM [Brazil Customers];
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```
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## ✅ 검증 상태 및 신뢰도
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- **상태:** draft
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- **검증 단계:** conceptual
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- **출처 신뢰도:** B (W3Schools — widely used educational reference, not a primary standards body)
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- **신뢰 점수:** 0.88
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- **중복 검사 결과:** 신규 생성 (New discovery)
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## 🔗 지식 그래프 (Knowledge Graph)
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- **상위/루트:** [[SQL Tutorial]]
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- **관련 개념:** [[SQL Select]], [[SQL Avg]], [[SQL Create Table]]
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- **참조 맥락:** 복잡한 쿼리를 재사용 가능한 가상 테이블로 감싸야 할 때 사용.
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## 📚 출처 (Sources)
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- [S1] W3Schools — SQL Views — https://www.w3schools.com/sql/sql_view.asp
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## 📝 변경 이력 (Change history)
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- 2026-07-04: Initial draft synthesized from the W3Schools "SQL Views" page (Astra wiki-curation, P-Reinforce v3.1 format).
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