PHP/MySQL: How can I save the output values of $result['COUNT(id)']?

Just try the following instead:

$query = "SELECT COUNT(id) as c FROM tab GROUP BY col";
 
mysql_select_db('db');
 
$result = mysql_query($query) or die(mysql_error());
 
while($row = mysql_fetch_assoc($result)) {
  echo $row["c"];
  echo "/n";
}

You cannot set $result to another value at the same time you are still retrieving values from $result. Just use another variable like $row instead.

On the other hand it is better to use "COUNT(id) as c", so that you have stored the values in "c".
2014-03-11 at 13:02

Why not try the following approach:

$query = "SELECT COUNT(id) FROM tab GROUP BY col";
 
mysql_select_db('db');
 
$result = mysql_query($query) or die(mysql_error());
 
while(list($c) = mysql_fetch_row($result)) {
  echo $c;
  echo "/n";
}

With using list($c) and mysql_fetch_row you do not have the problems arising from the associated array construct.

The function mysql_fetch_row retrieves data row for data row from the result and stores the values of the fields in an array. With list(), you can easily store the array values in variables so that you can easily use them in your script. If you have several fields in your table, you can use list() like list($x, $y, $z) for 3 fields, for example.
2014-03-19 at 13:45