PHPmysqli查询操作全解析

$host = 'localhost';
$username = 'root';
$password = '123456';
$database = 'test_db';
<p>// 创建连接
$mysqli = new mysqli($host, $username, $password, $database);</p><p>// 检查连接是否成功
if ($mysqli->connect_error) {
die('连接失败：' . $mysqli->connect_error);
}</p><p>// 设置字符集，避免中文乱码
$mysqli->set_charset('utf8mb4');</p>

$sql = "SELECT id, name, email FROM users WHERE status = ?";
$stmt = $mysqli->prepare($sql); // 预处理，防 SQL 注入
<p>$status = 1;
$stmt->bind_param('i', $status); // 'i' 表示整型参数
$stmt->execute();</p><p>$result = $stmt->get_result(); // 获取结果集</p><p>while ($row = $result->fetch_assoc()) {
echo "ID: {$row['id']}, 姓名: {$row['name']}, 邮箱: {$row['email']}<br>";
}</p><p>$stmt->close(); // 记得关闭语句</p>

$sql = "INSERT INTO users (name, email, status) VALUES (?, ?, ?)";
$stmt = $mysqli->prepare($sql);
<p>$name = '张三';
$email = 'zhangsan@example.com';
$status = 1;</p><p>$stmt->bind_param('ssi', $name, $email, $status);
$stmt->execute();</p><p>if ($stmt->affected_rows > 0) {
echo "新增成功，ID：" . $mysqli->insert_id;
} else {
echo "执行失败：" . $stmt->error;
}</p><p>$stmt->close();</p>

$result = $mysqli->query("SELECT * FROM config");
if ($result && $result->num_rows > 0) {
    while ($row = $result->fetch_assoc()) {
        echo $row['key'] . ' = ' . $row['value'] . '<br>';
    }
}
$result->free(); // 释放结果集