2nd/10_Wiki/Dev/Topic_PHP/PHP_MySQL_Connect.md

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
php-mysql-connect	PHP MySQL Connect	Programming_Language	draft	conceptual		MySQLi vs PDO PHP MySQL 연결		B	0.9	2026-07-04	2026-07-04			php programming w3schools mysql mysqli pdo	https://www.w3schools.com/php/php_mysql_connect.asp

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):

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).