Add or Show amount of items

Question

How best to add or show the amount of items in a mysql table using php.

For when I run this code the following error appears:
Warning: mysql_num_rows() expects parameter 1 to be resource, boolean given in H:\Web\root\index.php on line 89

$mysql_connection =  mysql_connect($web_host, $web_user, $web_pass);
        $mysql_connection_from_db = mysql_select_db($web_db);

        $command_ = "SELECT COUNT(`usr_id`) FROM `app_users`";      
        $mysql_query = mysql_query($command_);      

        $num = mysql_num_rows($mysql_query);

        if(0 == $num) { $PESSOAS = 0; }
        else{
            while($row = mysql_fetch_assoc($mysql_query)) 
            {
                $PESSOAS = $PESSOAS + 1;
            }
        }

Line 89:

$num = mysql_num_rows($mysql_query);

NOTE: The goal is that the user click to participate and he add a name any more an id in the table and when loading the page the php system shows how many items there are in that table, or in the case, $PESSOAS, determining the number of participants.

Answer 1

You can get the result straight with the mysql_fetch_assoc() or mysql_fetch_array().

$command_ = "SELECT COUNT(`usr_id`) FROM `app_users`";      
$result = mysql_fetch_assoc(mysql_query($command_));  

The COUNT() will always return only 1 line, so the error of your code, you are making a looping.

And a hint, don’t use the mysql_connect() he this deprecated, use the function mysqli_connect().

Answer 2

Worked that way!

On the basis of Jeferson Assis' reply I was able to understand that there is no need to execute

SELECT COUNT(*) FROM `participacoes` 

But rather execute:

SELECT * FROM `participacoes` 

And proceed with php:

$mysql_connection =  mysqli_connect($web_host, $web_user, $web_pass, $web_db);   
$sql = 'SELECT * FROM `participacoes`';             
$PESSOAS = mysqli_num_rows( mysqli_query( $mysql_connection , $sql ));

Note that I only used only so that the system counts the number of items not the total number of items:

$PESSOAS = mysqli_num_rows( mysqli_query( $mysql_connection , $sql ));

if it would not end up in an infinite loop and no data would be replenished.