有结果集的mysqli函数获取行数和列数

<?php
$mysqli=new mysqli("localhost", "root", "123456", "xsphpdb");

if(mysqli_connect_errno()){
echo "错误：".mysqli_connect_error();
exit;
}

//执行select语句，返回来的就是结果集（对象）

$sql="select id,name from shops where id <50";

$result=$mysqli->query($sql);

$rows=$result->num_rows;
$cols=$result->field_count;

echo "表中{$rows}行，{$cols}列<br>";

$mysqli->close();