PHP MySQL显示按公共字段分组的多行

<?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);
}

// 查询数据并按公共字段分组
$sql = "SELECT common_field, column1, column2 FROM table_name GROUP BY common_field";
$result = $conn->query($sql);

// 输出结果
if ($result->num_rows > 0) {
    while($row = $result->fetch_assoc()) {
        echo "公共字段: " . $row["common_field"]. " - 列1: " . $row["column1"]. " - 列2: " . $row["column2"]. "<br>";
    }
} else {
    echo "没有结果";
}

// 关闭数据库连接
$conn->close();
?>