---
id: sql-intro
title: "SQL Intro"
category: "Database"
status: "draft"
verification_status: "conceptual"
canonical_id: ""
aliases: ["SQL Introduction", "What is SQL", "SQL 소개", "Structured Query Language"]
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: ["sql", "database", "w3schools", "rdbms", "basics"]
raw_sources: ["https://www.w3schools.com/sql/sql_intro.asp"]
applied_in: []
github_commit: ""
---

# [[SQL Intro]]

## 🎯 한 줄 통찰 (One-line insight)
SQL is the ANSI/ISO-standard language for accessing and manipulating data in a Relational Database Management System (RDBMS), where data lives in tables made of rows and columns. [S1]

## 🧠 핵심 개념 (Core concepts)
- **SQL (Structured Query Language)** — a standard language for accessing and manipulating databases, standardized by ANSI (1986) and ISO (1987). [S1]
- **What SQL can do** — execute queries, retrieve/insert/update/delete records, create databases/tables/stored procedures/views, and set permissions on tables, procedures, and views. [S1]
- **Standard but fragmented** — although SQL is an ANSI/ISO standard, different database systems implement their own proprietary extensions on top of a common core (SELECT/UPDATE/DELETE/INSERT/WHERE). [S1]
- **RDBMS (Relational Database Management System)** — the basis for SQL and all modern database systems (MS SQL Server, IBM DB2, Oracle, MySQL, MS Access); data is stored in tables, where a column is a vertical entity and a record (row) is a horizontal entity. [S1]
- **Using SQL on a web site** — typically requires an RDBMS program (MS Access/SQL Server/MySQL), a server-side scripting language (PHP/ASP) to run SQL, and HTML/CSS to present the results. [S1]

## 🧩 추출된 패턴 (Extracted patterns)
- **Table = columns + rows** — every RDBMS models data as tables where columns define the schema and records (rows) hold the data. [S1]
- **Standard-core + vendor-extension** — expect the major commands to work everywhere, but expect proprietary extensions to differ per vendor. [S1]
- **Three-layer web stack** — RDBMS (data) + server-side language (logic) + HTML/CSS (presentation) is the classic pattern for a database-backed web site. [S1]

## 📖 세부 내용 (Details)
- SQL stands for **Structured Query Language** and lets you access and manipulate data stored in a database. [S1]
- It became a standard of the American National Standards Institute (ANSI) in 1986 and of the International Organization for Standardization (ISO) in 1987. [S1]
- Example table ("Customers") illustrates the RDBMS model:
```sql
SELECT * FROM Customers;
```
- The Customers example table has columns `CustomerID, CustomerName, ContactName, Address, City, PostalCode, Country`, and each row is one customer record. [S1]

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

## 🛠️ 적용 사례 (Applied in summary)
현재 발견된 실제 적용 사례가 없습니다 — 이 문서는 개론(Intro) 페이지로, 이후 SQL 튜토리얼 전체(SELECT/WHERE/JOIN 등)에서 여기서 정의한 RDBMS/테이블 모델이 반복 적용된다. [S1]

## 💻 코드 패턴 (Code patterns)
Select all records from a table (SQL):
```sql
SELECT * FROM Customers;
```

## ✅ 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 Syntax]], [[SQL Select]], [[SQL Create Table]]
- **참조 맥락:** SQL 튜토리얼 전체의 진입점 — RDBMS/테이블 모델을 처음 정의하는 문서.

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

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