PHP按日期和ID分组

<?php
// 连接数据库
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "database";
$conn = new mysqli($servername, $username, $password, $dbname);
if ($conn->connect_error) {
    die("连接失败: " . $conn->connect_error);
}

// 查询数据并按日期和ID分组
$sql = "SELECT * FROM your_table ORDER BY date, id";
$result = $conn->query($sql);
$groupedData = array();
while ($row = $result->fetch_assoc()) {
    $date = $row['date'];
    $id = $row['id'];
    $groupedData[$date][$id][] = $row;
}

// 输出分组后的数据
foreach ($groupedData as $date => $dateData) {
    echo "日期: " . $date . "<br>";
    foreach ($dateData as $id => $idData) {
        echo "ID: " . $id . "<br>";
        foreach ($idData as $row) {
            // 处理每一行数据
            echo "数据: " . $row['column1'] . ", " . $row['column2'] . "<br>";
        }
    }
}

// 关闭数据库连接
$conn->close();
?>