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Antigravity Agent e9cbf23ab5 docs(10_Wiki): Dev 폴더 누락분 반영 — Topic_Programming으로 통합

이전 재구성 작업에서 Dev/ 폴더가 누락되었던 것을 반영.

- Dev/Topic_Programming(중첩 폴더, 78개)은 Dev 자체 최상위 폴더들
  (Architecture/Conventions/Engineering_Intelligence 등)과 완전 중복이라 제거.
- Dev 최상위 엔지니어링 지식 폴더(Architecture/Conventions/Engineering_Intelligence/
  Failure_Library/Generalized_Principles/Language/Pattern_Catalog/Platform_Guides/
  Subsystems, 77개)는 이미 Topic_Programming/Topic_Programming에 더 최신 버전이
  존재해 중복 제거(고유 콘텐츠 1개는 예외 처리하여 이동 보존).
- Dev의 W3Schools 언어 튜토리얼 폴더(Topic_C/CPP/CSS/CSharp/HOWTO/HTML/Java/
  JavaScript/PHP/Python/SQL/W3CSS, 1201개)는 전부 Topic_Programming 하위로 이동.
- 에이전트 운영 상태(.astra/docs)는 그대로 유지, 콘텐츠 폴더만 정리.
- Topic_Programming 최종 문서 수: 2784 → 3985.

2026-07-05 00:39:13 +09:00

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title

SQL Avg

🎯 한 줄 통찰 (One-line insight)

AVG() returns a numeric column's mean, ignoring NULLs, and doubles as a comparison baseline when nested as a subquery in a WHERE clause. [S1]

🧠 핵심 개념 (Core concepts)

AVG() function — returns the average value of a numeric column; ignores NULL values. [S1]
Syntax — SELECT AVG(column_name) FROM table_name WHERE condition;. [S1]
AVG() with GROUP BY — returns the average per group. [S1]

🧩 추출된 패턴 (Extracted patterns)

AVG() as a subquery baseline — WHERE Price > (SELECT AVG(Price) FROM Products) uses AVG() inside a subquery to compare each row against the overall average — a reusable pattern for "above/below average" filters. [S1]

📖 세부 내용 (Details)

Basic average: SELECT AVG(Price) FROM Products;. [S1]
With WHERE: SELECT AVG(Price) FROM Products WHERE CategoryID = 1;. [S1]
With alias: SELECT AVG(Price) AS [average price] FROM Products;. [S1]
Above-average filter via subquery: SELECT * FROM Products WHERE Price > (SELECT AVG(Price) FROM Products);. [S1]
With GROUP BY: SELECT AVG(Price) AS AveragePrice, CategoryID FROM Products GROUP BY CategoryID;. [S1]

⚖️ 모순 및 업데이트 (Contradictions & updates)

소스에서 모순되는 정보는 발견되지 않음.

🛠️ 적용 사례 (Applied in summary)

현재 발견된 실제 적용 사례가 없습니다 — "평균 이상/이하" 필터링은 실무 리포트에서 흔한 패턴이다. [S1]

💻 코드 패턴 (Code patterns)

Above-average filter using AVG() as subquery (SQL):

SELECT * FROM Products
WHERE Price > (SELECT AVG(Price) FROM Products);

✅ 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 Aggregate Functions, SQL Group By, SQL Where
참조 맥락: 평균값 계산 및 평균 대비 비교 필터링의 기본 함수.

📚 출처 (Sources)

[S1] W3Schools — SQL AVG() Function — https://www.w3schools.com/sql/sql_avg.asp

📝 변경 이력 (Change history)

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

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