how to get data from data base and prints if it is followed the condition

how to get data from data base and prints if it is followed the condition
<?php
require 'dbconnect.php';
$query = 'SELECT `first` , `last` FROM `a_database` WHERE `id`<5  ORDER BY `id` ';	id<5 , then only runs, if id<3, it prints upto 3
if($query_run = @mysqli_query($mycon, $query)){
if(mysqli_num_rows($query_run)! = NULL){	if rows are not null, then while executes
while($row = @mysqli_fetch_assoc($query_run)){
$fname = @mysqli_fetch_assoc;
$sname = $row['last'];
echo $fname .''.$sname .'</br></br>';
}
}else{ echo 'no users found';
}else {
echo 'queryfailed';
}
?>

multi dimensional arrays
https://web-developer-tuts.blogspot.com/2020/06/arrays-and-associative-arrays.html

/*
$laptop = array(
array ("rahul", "dell", 10),	array in array called 2 d array
array ('sonam", "hp", 20),
array ("sumit", "zed", 30)
};
*/
$laptop [0][] = "rahul";
$laptop [0][] = 'dell';
$laptop[0][] = 10;

	require
how to write the query to do action	write query
how to execute query against connected database	@mysqli_query
how to find number of rows	mysqli_num_rows
how to convert tables to associative arrays	@mysqli_fetch_assoc
how to acess data as a row	@mysqli_fetch_assoc
	if if while else else