mysqli 输出错误

$mysqli = new mysqli("localhost", "username", "password", "database");

if ($mysqli->connect_errno) {
    echo "Failed to connect to MySQL: " . $mysqli->connect_error;
    exit();
}

$result = $mysqli->query("SELECT * FROM non_existent_table");

if (!$result) {
    echo "Query failed: " . $mysqli->error;
}

<?php
$host = 'localhost';
$user = 'username';
$password = 'password';
$dbname = 'database_name';

// 创建连接
$mysqli = new mysqli($host, $user, $password, $dbname);

// 检查连接
if ($mysqli->connect_error) {
    die('Connect Error (' . $mysqli->connect_errno . ') ' . $mysqli->connect_error);
}

// 执行查询
$sql = "SELECT id, name FROM users";
$result = $mysqli->query($sql);

if ($result) {
    // 输出结果
    while ($row = $result->fetch_assoc()) {
        echo "ID: " . $row['id'] . " - Name: " . $row['name'] . "<br>";
    }
    // 释放结果集
    $result->free();
} else {
    echo "Error: " . $mysqli->error;
}

// 关闭连接
$mysqli->close();
?>