---
id: sql-parameters
title: "SQL Parameters"
category: "Database"
status: "draft"
verification_status: "conceptual"
canonical_id: ""
aliases: ["Parameterized Queries", "SQL 파라미터화 쿼리"]
duplicate_of: ""
source_trust_level: "B"
confidence_score: 0.87
created_at: 2026-07-04
updated_at: 2026-07-04
review_reason: ""
merge_history: []
tags: ["sql", "database", "w3schools", "security", "parameters"]
raw_sources: ["https://www.w3schools.com/sql/sql_parameterized_queries.asp"]
applied_in: []
github_commit: ""
---

# [[SQL Parameters]]

## 🎯 한 줄 통찰 (One-line insight)
Parameterized queries fix SQL injection by sending user input as placeholder-bound values instead of concatenated text, so the database always treats the input literally, never as executable SQL. [S1]

## 🧠 핵심 개념 (Core concepts)
- **Parameterized query** — an SQL statement using placeholders instead of directly embedding input values in the query text; placeholders are replaced with actual values at execution time. [S1]
- **Placeholder syntax varies by vendor** — MySQL uses `?`, SQL Server uses `@`, PostgreSQL uses `$`. [S1]
- **Literal treatment guarantee** — the SQL engine checks each parameter against its column type and treats it literally, not as part of the executable SQL — this is what neutralizes injection. [S1]

## 🧩 추출된 패턴 (Extracted patterns)
- **Same fix for SELECT and INSERT** — the parameterization pattern applies identically whether reading (`SELECT ... WHERE UserId = @userid`) or writing (`INSERT INTO ... VALUES(@cname, @caddress, @ccity)`). [S1]
- **Bind-then-execute in application code** — frameworks like ASP.NET separate building the query text (with placeholders) from binding actual values (`cmd.Parameters.AddWithValue(...)`), directly countering the string-concatenation root cause from [[SQL Injection]]. [S1]

## 📖 세부 내용 (Details)
- SQL Server-style placeholder query: `query = "SELECT * FROM Users WHERE UserId = @userid"; db.Execute(query, userid);`. [S1]
- Parameterized INSERT: `query = "INSERT INTO Customers (CustomerName, Address, City) Values(@cname, @caddress, @ccity)"; db.Execute(query, cname, caddress, ccity);`. [S1]
- ASP.NET binding pattern: `cmd = new SqlCommand(query); cmd.Parameters.AddWithValue("@userid", userid); cmd.ExecuteReader();`. [S1]

## ⚖️ 모순 및 업데이트 (Contradictions & updates)
소스에서 모순되는 정보는 발견되지 않음.

## 🛠️ 적용 사례 (Applied in summary)
현재 발견된 실제 적용 사례가 없습니다 — 앞서 SQL Injection 챕터에서 보여준 문자열 연결(concatenation) 취약점을 직접 해소하는 대응책이다. [S1]

## 💻 코드 패턴 (Code patterns)
Parameterized SELECT (ASP.NET, SQL Server style):
```
userid = getRequestString("UserId");
query = "SELECT * FROM Customers WHERE CustomerId = @userid";
cmd = new SqlCommand(query);
cmd.Parameters.AddWithValue("@userid", userid);
cmd.ExecuteReader();
```

## ✅ 검증 상태 및 신뢰도
- **상태:** draft
- **검증 단계:** conceptual
- **출처 신뢰도:** B (W3Schools — widely used educational reference, not a primary standards body)
- **신뢰 점수:** 0.87
- **중복 검사 결과:** 신규 생성 (New discovery)

## 🔗 지식 그래프 (Knowledge Graph)
- **상위/루트:** [[SQL Tutorial]]
- **관련 개념:** [[SQL Injection]], [[SQL Prepared Statements]]
- **참조 맥락:** SQL Injection의 직접적인 대응책 — Prepared Statements와 함께 사용자 입력을 다루는 표준 방어법.

## 📚 출처 (Sources)
- [S1] W3Schools — SQL Parameters — https://www.w3schools.com/sql/sql_parameterized_queries.asp

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