PHP对没有WHERE子句的列进行计数

<?php
// 连接数据库
$servername = "localhost";
$username = "your_username";
$password = "your_password";
$dbname = "your_database";

$conn = new mysqli($servername, $username, $password, $dbname);
if ($conn->connect_error) {
    die("连接失败: " . $conn->connect_error);
}

// 执行查询
$sql = "SELECT COUNT(column_name) AS count FROM table_name";
$result = $conn->query($sql);

// 处理结果
if ($result->num_rows > 0) {
    $row = $result->fetch_assoc();
    $count = $row["count"];
    echo "列的计数结果为: " . $count;
} else {
    echo "没有找到匹配的记录";
}

// 关闭连接
$conn->close();
?>