2nd/10_Wiki/Topics/Topic_Programming/Topic_SQL/SQL_Views.md

id, title, category, status, verification_status, canonical_id, aliases, duplicate_of, source_trust_level, confidence_score, created_at, updated_at, review_reason, merge_history, tags, raw_sources, applied_in, github_commit

id	title	category	status	verification_status	canonical_id	aliases	duplicate_of	source_trust_level	confidence_score	created_at	updated_at	review_reason	merge_history	tags	raw_sources	applied_in	github_commit
sql-views	SQL Views	Database	draft	conceptual		SQL CREATE VIEW Statement SQL View 가상 테이블		B	0.88	2026-07-04	2026-07-04			sql database w3schools view	https://www.w3schools.com/sql/sql_view.asp

SQL Views

🎯 한 줄 통찰 (One-line insight)

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]

🧠 핵심 개념 (Core concepts)

• SQL view — a virtual table based on the result-set of an SQL statement; fields come from one or more real tables. [S1]
• 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]
• Syntax (create) — CREATE VIEW view_name AS SELECT column1, column2, ... FROM table_name WHERE condition;. [S1]
• Querying a view — SELECT * FROM view_name;, exactly like querying a real table. [S1]
• Updating a view — ALTER VIEW (SQL Server) vs. CREATE OR REPLACE VIEW (MySQL/Oracle). [S1]
• Dropping a view — DROP VIEW view_name;. [S1]

🧩 추출된 패턴 (Extracted patterns)

• 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]

📖 세부 내용 (Details)

• Simple filtered view: CREATE VIEW [Brazil Customers] AS SELECT CustomerName, ContactName FROM Customers WHERE Country = 'Brazil';, queried as SELECT * FROM [Brazil Customers];. [S1]
• View wrapping a subquery: CREATE VIEW [Products Above Average Price] AS SELECT ProductName, Price FROM Products WHERE Price > (SELECT AVG(Price) FROM Products);. [S1]
• Update a view (SQL Server): ALTER VIEW [Brazil Customers] AS SELECT CustomerName, ContactName, City FROM Customers WHERE Country = 'Brazil';. [S1]
• Update a view (MySQL/Oracle): CREATE OR REPLACE VIEW [Brazil Customers] AS SELECT CustomerName, ContactName, City FROM Customers WHERE Country = 'Brazil';. [S1]
• Drop a view: DROP VIEW [Brazil Customers];. [S1]

⚖️ 모순 및 업데이트 (Contradictions & updates)

• 뷰 갱신 문법이 벤더별로 다름: SQL Server는 ALTER VIEW, MySQL/Oracle은 CREATE OR REPLACE VIEW를 사용. [S1]

🛠️ 적용 사례 (Applied in summary)

현재 발견된 실제 적용 사례가 없습니다 — AVG() 서브쿼리를 뷰로 감싸 재사용 가능한 이름으로 노출하는 예시가 소스에 직접 등장한다. [S1]

💻 코드 패턴 (Code patterns)

Create and query a view (SQL):

CREATE VIEW [Brazil Customers] AS
SELECT CustomerName, ContactName
FROM Customers
WHERE Country = 'Brazil';

SELECT * FROM [Brazil Customers];

✅ 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 Select, SQL Avg, SQL Create Table
• 참조 맥락: 복잡한 쿼리를 재사용 가능한 가상 테이블로 감싸야 할 때 사용.

📚 출처 (Sources)

• [S1] W3Schools — SQL Views — https://www.w3schools.com/sql/sql_view.asp

📝 변경 이력 (Change history)

• 2026-07-04: Initial draft synthesized from the W3Schools "SQL Views" page (Astra wiki-curation, P-Reinforce v3.1 format).