PHP & MySQL -如何统计每天的访问量

<?php
// 连接到MySQL数据库
$conn = mysqli_connect("localhost", "username", "password", "database");

// 检查连接是否成功
if (!$conn) {
    die("连接数据库失败: " . mysqli_connect_error());
}

// 获取当前日期
$currentDate = date("Y-m-d");

// 检查数据库中是否已存在当前日期的记录
$sql = "SELECT * FROM access_stats WHERE date = '$currentDate'";
$result = mysqli_query($conn, $sql);

if (mysqli_num_rows($result) > 0) {
    // 如果存在记录，则将访问量加1
    $row = mysqli_fetch_assoc($result);
    $count = $row['count'] + 1;
    $sql = "UPDATE access_stats SET count = $count WHERE date = '$currentDate'";
    mysqli_query($conn, $sql);
} else {
    // 如果不存在记录，则插入一条新记录
    $sql = "INSERT INTO access_stats (date, count) VALUES ('$currentDate', 1)";
    mysqli_query($conn, $sql);
}

// 查询每天的访问量并显示在页面上
$sql = "SELECT date, SUM(count) AS total_count FROM access_stats GROUP BY date";
$result = mysqli_query($conn, $sql);

if (mysqli_num_rows($result) > 0) {
    while ($row = mysqli_fetch_assoc($result)) {
        echo "日期: " . $row['date'] . "，访问量: " . $row['total_count'] . "<br>";
    }
} else {
    echo "暂无访问数据";
}

// 关闭数据库连接
mysqli_close($conn);
?>