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3.5 KiB
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 | ||||||||||
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| sql-having | SQL Having | Database | draft | conceptual |
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B | 0.9 | 2026-07-04 | 2026-07-04 |
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SQL Having
🎯 한 줄 통찰 (One-line insight)
HAVING filters GROUP BY results based on aggregate conditions, applying AFTER grouping — unlike WHERE, which filters individual rows BEFORE grouping. [S1]
🧠 핵심 개념 (Core concepts)
- HAVING clause — filters the results of a GROUP BY query based on aggregate functions. [S1]
- WHERE vs. HAVING — WHERE filters individual rows before grouping; HAVING filters groups after aggregation. [S1]
- Syntax —
SELECT column1, aggregate_function(column2), column3, ... FROM table_name WHERE condition GROUP BY column1, column3 HAVING condition ORDER BY column_name;. [S1]
🧩 추출된 패턴 (Extracted patterns)
- WHERE + GROUP BY + HAVING composition — a query can filter rows first (WHERE), group them, then filter the resulting groups (HAVING) — e.g. restrict to two named employees, group by last name, then keep only groups with more than 25 orders. [S1]
📖 세부 내용 (Details)
- Countries with more than 5 customers:
SELECT Country, COUNT(CustomerID) AS [Number of Customers] FROM Customers GROUP BY Country HAVING COUNT(CustomerID) > 5;. [S1] - Same, sorted descending:
... GROUP BY Country HAVING COUNT(CustomerID) > 5 ORDER BY COUNT(CustomerID) DESC;. [S1] - Employees with more than 10 orders, via JOIN + GROUP BY + HAVING:
SELECT Employees.LastName, COUNT(Orders.OrderID) AS NumberOfOrders FROM Orders INNER JOIN Employees ON Orders.EmployeeID = Employees.EmployeeID GROUP BY LastName HAVING COUNT(Orders.OrderID) > 10;. [S1] - Combined WHERE + GROUP BY + HAVING: filter to two named employees first, then keep only those with more than 25 orders. [S1]
⚖️ 모순 및 업데이트 (Contradictions & updates)
소스에서 모순되는 정보는 발견되지 않음.
🛠️ 적용 사례 (Applied in summary)
현재 발견된 실제 적용 사례가 없습니다 — "N건 이상인 그룹만 보기" 같은 리포팅 쿼리에서 GROUP BY와 항상 짝을 이뤄 쓰인다. [S1]
💻 코드 패턴 (Code patterns)
Filter groups by aggregate condition (SQL):
SELECT Country, COUNT(CustomerID) AS [Number of Customers]
FROM Customers
GROUP BY Country
HAVING COUNT(CustomerID) > 5;
✅ 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 Group By, SQL Where, SQL Aggregate Functions
- 참조 맥락: GROUP BY 결과 자체를 조건으로 걸러야 할 때 사용 — WHERE와 역할을 혼동하지 않는 것이 핵심.
📚 출처 (Sources)
- [S1] W3Schools — SQL HAVING Clause — https://www.w3schools.com/sql/sql_having.asp
📝 변경 이력 (Change history)
- 2026-07-04: Initial draft synthesized from the W3Schools "SQL HAVING Clause" page (Astra wiki-curation, P-Reinforce v3.1 format).