---
id: php-ajax-database
title: "PHP AJAX Database"
category: "Programming_Language"
status: "draft"
verification_status: "conceptual"
canonical_id: ""
aliases: ["AJAX MySQL", "PHP AJAX 데이터베이스"]
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: ["php", "programming", "w3schools", "ajax", "mysql"]
raw_sources: ["https://www.w3schools.com/php/php_ajax_database.asp"]
applied_in: []
github_commit: ""
---

# [[PHP AJAX Database]]

## 🎯 한 줄 통찰 (One-line insight)
This chapter is the exact same AJAX architecture as the name-autocomplete example, but with the PHP endpoint querying a REAL MySQL database instead of a hardcoded array — the JS-side `showUser()` function and event-handling boilerplate barely change, proving the AJAX pattern is agnostic to where the PHP script actually gets its data. [S1]

## 🧠 핵심 개념 (Core concepts)
- **`onchange` event** (vs. `onkeyup` in the earlier example) — triggers on dropdown selection instead of every keystroke. [S1]
- **Same AJAX skeleton** — `XMLHttpRequest` + `onreadystatechange` + query-string parameter passing, identical to the previous chapter. [S1]
- **PHP-side database query** — `intval($_GET['q'])` sanitizes the ID as an integer, then a `SELECT * FROM user WHERE id = '$q'` query runs against MySQLi. [S1]
- **Response is a rendered HTML table** — the PHP script builds `<table>` markup directly from the query results and echoes it, which JavaScript injects wholesale into the placeholder div. [S1]

## 📖 세부 내용 (Details)
- Dropdown trigger: `<select name="users" onchange="showUser(this.value)">`. [S1]
- PHP query and HTML table generation: `$q = intval($_GET['q']); $con = mysqli_connect('localhost','peter','abc123'); mysqli_select_db($con,"ajax_demo"); $sql="SELECT * FROM user WHERE id = '".$q."'"; $result = mysqli_query($con,$sql); echo "<table>..."; while($row = mysqli_fetch_array($result)) { echo "<tr><td>" . $row['FirstName'] . "</td>...</tr>"; } echo "</table>";`. [S1]

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

## 🛠️ 적용 사례 (Applied in summary)
현재 발견된 실제 적용 사례가 없습니다 — 드롭다운에서 인물을 선택하면 MySQL에서 정보를 조회해 테이블로 보여주는 것이 AJAX-DB 연동의 대표 실전 사례다. [S1]

## 💻 코드 패턴 (Code patterns)
PHP endpoint querying MySQL and returning an HTML table for AJAX (PHP):
```php
$q = intval($_GET['q']);
$con = mysqli_connect('localhost', 'peter', 'abc123');
mysqli_select_db($con, "ajax_demo");
$sql = "SELECT * FROM user WHERE id = '" . $q . "'";
$result = mysqli_query($con, $sql);
echo "<table>...";
while ($row = mysqli_fetch_array($result)) {
    echo "<tr><td>" . $row['FirstName'] . "</td></tr>";
}
echo "</table>";
```

## ✅ 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:** [[PHP Tutorial]]
- **관련 개념:** [[PHP AJAX PHP]], [[PHP MySQL Select]], [[PHP AJAX XML]]
- **참조 맥락:** AJAX+MySQL 연동 — XML 데이터 연동(AJAX XML) 챕터로 이어짐.

## 📚 출처 (Sources)
- [S1] W3Schools — PHP - AJAX and MySQL — https://www.w3schools.com/php/php_ajax_database.asp

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