---
id: python-mongodb-find
title: "Python MongoDB Find"
category: "Programming_Language"
status: "draft"
verification_status: "conceptual"
canonical_id: ""
aliases: ["find()", "find_one()", "projection", "파이썬 MongoDB 조회"]
duplicate_of: ""
source_trust_level: "B"
confidence_score: 0.9
created_at: 2026-07-04
updated_at: 2026-07-04
review_reason: ""
merge_history: []
tags: ["python", "mongodb", "w3schools", "find", "projection"]
raw_sources: ["https://www.w3schools.com/python/python_mongodb_find.asp"]
applied_in: []
github_commit: ""
---

# [[Python MongoDB Find]]

## 🎯 한 줄 통찰 (One-line insight)
The find() projection object can't mix 0s and 1s (except for `_id`) — including one field with `1` implicitly excludes everything else, while excluding one field with `0` implicitly includes everything else; mixing both raises an error. [S1]

## 🧠 핵심 개념 (Core concepts)
- **`find_one()`** — returns the first matching document. [S1]
- **`find()`** — returns ALL matching documents; empty query object = all documents (like `SELECT *`). [S1]
- **Projection (2nd parameter)** — an object specifying which fields to include (`1`) or exclude (`0`); optional. [S1]
- **`_id` exception** — the only field allowed to mix with either 0 or 1 alongside the other fields. [S1]
- **Mixing 0 and 1 on non-`_id` fields is an error** — pick one style: either include specific fields (`1`) or exclude specific fields (`0`), not both. [S1]

## 🧩 추출된 패턴 (Extracted patterns)
- **Implicit-opposite rule** — specifying `1` for one field implicitly sets all UNMENTIONED fields to `0`, and vice versa — this is why mixing explicit `0`s and `1`s (beyond `_id`) is contradictory and rejected. [S1]

## 📖 세부 내용 (Details)
- Find one: `x = mycol.find_one(); print(x)`. [S1]
- Find all: `for x in mycol.find(): print(x)`. [S1]
- Include only specific fields: `for x in mycol.find({},{"_id": 0, "name": 1, "address": 1}): print(x)`. [S1]
- Exclude one field: `for x in mycol.find({},{"address": 0}): print(x)`. [S1]
- Invalid mix (raises error): `mycol.find({},{"name": 1, "address": 0})`. [S1]

## ⚖️ 모순 및 업데이트 (Contradictions & updates)
소스에서 모순되는 정보는 발견되지 않음. `_id` 필드만 예외적으로 0/1 혼용이 허용된다는 규칙이 명시됨. [S1]

## 🛠️ 적용 사례 (Applied in summary)
현재 발견된 실제 적용 사례가 없습니다 — SQL의 SELECT 컬럼 지정과 개념적으로 대응하지만, 문법은 0/1 규칙이라는 독특한 방식이다. [S1]

## 💻 코드 패턴 (Code patterns)
Include only specific fields, excluding _id (Python):
```python
for x in mycol.find({}, {"_id": 0, "name": 1, "address": 1}):
    print(x)
```

## ✅ 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:** [[Python Tutorial]]
- **관련 개념:** [[Python MongoDB Query]], [[Python MongoDB Insert]], [[Python MySQL Select]]
- **참조 맥락:** SQL SELECT의 컬럼 지정에 대응 — 0/1 프로젝션 규칙이 핵심.

## 📚 출처 (Sources)
- [S1] W3Schools — Python MongoDB Find — https://www.w3schools.com/python/python_mongodb_find.asp

## 📝 변경 이력 (Change history)
- 2026-07-04: Initial draft synthesized from the W3Schools "Python MongoDB Find" page (Astra wiki-curation, P-Reinforce v3.1 format).
