找出来自两个不同数据库查询的两个计数列之间的差异，并在PHP中显示结果

// 连接到第一个数据库
$mysqli1 = mysqli_connect("hostname", "username", "password", "database1");

// 执行第一个查询
$query1 = "SELECT COUNT(*) FROM table1";
$result1 = mysqli_query($mysqli1, $query1);
$count1 = mysqli_fetch_row($result1)[0];

// 连接到第二个数据库
$mysqli2 = mysqli_connect("hostname", "username", "password", "database2");

// 执行第二个查询
$query2 = "SELECT COUNT(*) FROM table2";
$result2 = mysqli_query($mysqli2, $query2);
$count2 = mysqli_fetch_row($result2)[0];

// 计算差异
$difference = $count1 - $count2;

// 显示结果
echo "差异值为：" . $difference;