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- Topic_Graphic → Domain_Design
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- Topic_General → Domain_General
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Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
2026-07-11 11:05:56 +09:00

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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-dates SQL Dates Database draft conceptual
SQL Working With Dates
SQL 날짜
B 0.88 2026-07-04 2026-07-04
sql
database
w3schools
dates
https://www.w3schools.com/sql/sql_dates.asp

SQL Dates

🎯 한 줄 통찰 (One-line insight)

Matching a date literal against a datetime column silently returns nothing if the stored value carries a time component the literal doesn't — the hardest part of SQL dates is format alignment, not date logic itself. [S1]

🧠 핵심 개념 (Core concepts)

  • The core difficulty — being sure the date format you insert/select matches the database column's format. [S1]
  • MySQL date typesDATE (YYYY-MM-DD), DATETIME/TIMESTAMP (YYYY-MM-DD HH:MI:SS), TIME (HH:MI:SS), YEAR (YYYY or YY). [S1]
  • SQL Server date typesDATE, DATETIME, SMALLDATETIME, TIME, TIMESTAMP (a unique number, not a date). [S1]

🧩 추출된 패턴 (Extracted patterns)

  • Time-component footgun — a WHERE clause like OrderDate='2025-11-11' matches rows when the column is pure DATE, but silently returns zero rows once the column stores a time component too (e.g. 2025-11-11 13:23:44), because exact string/value equality no longer holds. [S1]
  • Keep dates time-free unless necessary — the source explicitly recommends avoiding time-components in date columns to keep queries simple, unless the time is actually needed. [S1]

📖 세부 내용 (Details)

  • Simple date match (works, no time component): SELECT * FROM Orders WHERE OrderDate='2025-11-11'. [S1]
  • Same query against a column that also stores time (returns NO rows, since exact match requires the time portion too): same query, different schema. [S1]

⚖️ 모순 및 업데이트 (Contradictions & updates)

소스에서 모순되는 정보는 발견되지 않음. 다만 "동일해 보이는 쿼리가 스키마에 따라 결과가 완전히 달라진다"는 점이 핵심 경고로 제시됨. [S1]

🛠️ 적용 사례 (Applied in summary)

현재 발견된 실제 적용 사례가 없습니다 — "쿼리가 아무 결과도 안 준다"는 흔한 버그의 원인이 날짜/시간 포맷 불일치인 경우가 많다. [S1]

💻 코드 패턴 (Code patterns)

Exact date match, no time component (SQL):

SELECT * FROM Orders WHERE OrderDate='2025-11-11';

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)

📚 출처 (Sources)

📝 변경 이력 (Change history)

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