PHP でデータベース クエリと結果のページネーションを使用するにはどうすればよいですか?

<?php
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "database";

// 创建数据库连接
$conn = new mysqli($servername, $username, $password, $dbname);

// 检查连接是否成功
if ($conn->connect_error) {
    die("连接失败: " . $conn->connect_error);
}

// 执行查询语句
$sql = "SELECT * FROM users";
$result = $conn->query($sql);

// 检查查询结果是否为空
if ($result->num_rows > 0) {
    // 输出每行数据
    while($row = $result->fetch_assoc()) {
        echo "用户名: " . $row["username"]. " - 邮箱: " . $row["email"]. "<br>";
    }
} else {
    echo "没有查询到结果";
}

// 关闭数据库连接
$conn->close();
?>

<?php
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "database";

// 创建数据库连接
$conn = new mysqli($servername, $username, $password, $dbname);

// 检查连接是否成功
if ($conn->connect_error) {
    die("连接失败: " . $conn->connect_error);
}

// 每页显示的数据量
$pageSize = 10;
// 当前页码
$page = isset($_GET['page']) ? $_GET['page'] : 1;

// 计算总数据量
$sqlCount = "SELECT COUNT(*) as total FROM users";
$countResult = $conn->query($sqlCount);
$total = $countResult->fetch_assoc()["total"];

// 计算总页数
$totalPages = ceil($total / $pageSize);

// 计算起始索引
$startIndex = ($page - 1) * $pageSize;

// 查询当前页的数据
$sql = "SELECT * FROM users LIMIT $startIndex, $pageSize";
$result = $conn->query($sql);

// 输出当前页的数据
if ($result->num_rows > 0) {
    while($row = $result->fetch_assoc()) {
        echo "用户名: " . $row["username"]. " - 邮箱: " . $row["email"]. "<br>";
    }
} else {
    echo "没有查询到结果";
}

// 输出分页链接
for ($i = 1; $i <= $totalPages; $i++) {
    echo "<a href='?page=$i'>$i</a>";
}

// 关闭数据库连接
$conn->close();
?>