---
id: php-mysql-connect
title: "PHP MySQL Connect"
category: "Programming_Language"
status: "draft"
verification_status: "conceptual"
canonical_id: ""
aliases: ["MySQLi vs PDO", "PHP MySQL 연결"]
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: ["php", "programming", "w3schools", "mysql", "mysqli", "pdo"]
raw_sources: ["https://www.w3schools.com/php/php_mysql_connect.asp"]
applied_in: []
github_commit: ""
---

# [[PHP MySQL Connect]]

## 🎯 한 줄 통찰 (One-line insight)
Switching database systems later is trivial with PDO (change the connection string + a few queries) but requires rewriting EVERYTHING with MySQLi (queries included) — since PDO works across 12 different database systems while MySQLi only works with MySQL, the choice between them is really a bet on whether the project will ever need to migrate databases. [S1]

## 🧠 핵심 개념 (Core concepts)
- **MySQLi (MySQL Improved)** — works only with MySQL; offers both object-oriented AND procedural APIs. [S1]
- **PDO (PHP Data Objects)** — works across 12 different database systems; object-oriented only. [S1]
- **Both support Prepared Statements** — critical for protecting against SQL injection. [S1]
- **Connection requires 4 pieces** — server name, username, password, database name. [S1]
- **PDO's exception-based error handling** — `PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION` — throws exceptions on query problems, caught via `catch(PDOException $e)`. [S1]
- **Closing connections** — automatic at script end; can be forced early via `$conn->close()` (MySQLi OOP), `mysqli_close($conn)` (procedural), or `$conn = null;` (PDO). [S1]

## 📖 세부 내용 (Details)
- MySQLi OOP connection: `$conn = new mysqli($servername, $username, $password, $dbname); if ($conn->connect_error) { die("Connection failed: " . $conn->connect_error); }`. [S1]
- MySQLi procedural connection: `$conn = mysqli_connect($servername, $username, $password, $dbname); if (!$conn) { die("Connection failed: " . mysqli_connect_error()); }`. [S1]
- PDO connection: `try { $conn = new PDO("mysql:host=$servername;dbname=$dbname", $username, $password); $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION); } catch(PDOException $e) { echo "Connection failed: " . $e->getMessage(); }`. [S1]

## ⚖️ 모순 및 업데이트 (Contradictions & updates)
- **DB 전환 용이성의 차이**: PDO는 다른 DB로 전환 시 연결 문자열과 일부 쿼리만 수정하면 되지만, MySQLi는 쿼리를 포함한 전체 코드를 다시 작성해야 한다는 점이 명확히 대비됨. [S1]

## 🛠️ 적용 사례 (Applied in summary)
현재 발견된 실제 적용 사례가 없습니다 — PDO의 예외 기반 에러 처리(ERRMODE_EXCEPTION)가 데이터베이스 연결 문제를 안전하게 다루는 표준 패턴이다. [S1]

## 💻 코드 패턴 (Code patterns)
PDO connection with exception-based error handling (PHP):
```php
try {
    $conn = new PDO("mysql:host=$servername;dbname=$dbname", $username, $password);
    $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
    echo "Connected successfully";
} catch (PDOException $e) {
    echo "Connection failed: " . $e->getMessage();
}
```

## ✅ 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:** [[PHP Tutorial]]
- **관련 개념:** [[PHP MySQL Intro]], [[PHP MySQL Create DB]], [[PHP Exception]]
- **참조 맥락:** MySQLi/PDO 연결 방식 — 데이터베이스 생성(Create DB) 챕터로 이어짐.

## 📚 출처 (Sources)
- [S1] W3Schools — PHP Connect to MySQL — https://www.w3schools.com/php/php_mysql_connect.asp

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