PHP에서 mysql 레코드 수를 쿼리하는 방법

$sql = "SELECT id, firstname, lastname FROM MyGuests";
$result = mysqli_query($conn, $sql);
 
num_rows=mysqli_num_rows($result);

<?php
$link = mysql_connect("localhost", "mysql_user", "mysql_password");
mysql_select_db("database", $link);
 
$result = mysql_query("SELECT * FROM table1", $link);
$num_rows = mysql_num_rows($result);
echo "$num_rows Rows\n";
?>

<?php
$link = mysql_connect("localhost", "mysql_user", "mysql_password");
mysql_select_db("database", $link);
 
$result = mysql_query("SELECT COUNT(*) FROM table1", $link);
list($num_rows) = mysql_fetch_row($result);
echo "$num_rows Rows\n";
?>