PHP MySQL Count rows from INNER JOIN - GROUP BY - php

Question

What I'm trying to do here, is I want to output the count of the id and user_id columns from items, by users which have the rank 1.
Let's say there's 8 rows in items which have a base_item of 400, and these 8 rows, where 2 rows of them has a user_id of 4 and the existing left has a user_id of 6 The output should then be:
$countItems = 8 and $countUsers = 2.
$stmt = $conn->pdo->prepare("
SELECT COUNT(*),`user_id` FROM `items`
INNER JOIN `users`
ON `users`.`id` = `items`.`user_id`
WHERE `base_item` = :i AND `rank` = 1
GROUP BY `user_id`,`items`.`id`
");
$data = array(':i' => '400'); // item_id in `values` table
$stmt->execute($data);
if($inv = $stmt->fetch($db->FETCH_ASSOC)) {
$countItems = $inv['id'];
$countUsers = $inv['user_id'];
}
I have tried several methods, but I still keep getting output 2 and 2 even though the results should be 8 and 2.
Table Info for values:
Table Info for items:

Answer 1

First of all you never want to fetchAll() and discard the data just to count the number of rows. There is a better way.
SELECT COUNT(*) FROM `items` WHERE `base_item` = :item AND `user_id` = :uid
Secondly, you should try to avoid a nested loop whenever possible because nested loops don't scale very well. And the solution is to use a join or a subquery. You haven't posted your table structures, so this query is untested.
SELECT COUNT(*), user_id FROM `items` INNER JOIN users
ON users.id = items.user_id
WHERE `base_item` = :item and rank =1 GROUP BY user_id
One query instead of two, a lot less number of lines of code.

Answer 2

Problem is that you're replacing $smst withing the foreach loop.
Use other variable name, for example:
$stmt->execute();
foreach($stmt as $user) {
$stmt2 = $conn->pdo->prepare("SELECT `id`,`user_id` FROM `items` WHERE `base_item` = :item AND `user_id` = :uid");
$stmt2->bindParam(':item', $cmsval['item_id'], $db->PARAM_INT);
$stmt2->bindParam(':uid', $user['id'], $db->PARAM_INT);

Answer 3

Well, all I actually had to do, was remove GROUP BY and add COUNT DISTINCT instead, like following:
$stmt = $conn->pdo->prepare("
SELECT COUNT(DISTINCT `user_id`) as `uid`,
COUNT(`items`.`id`) as `id`
FROM `items`
INNER JOIN `users`
ON `users`.`id` = `items`.`user_id`
WHERE `base_item` = :i AND `rank` = 1
");
$stmt->bindParam(':i', $cmsval['item_id'], $db->PARAM_INT);
$stmt->execute();
if($inv = $stmt->fetch($db->FETCH_ASSOC)) {
$countItems = $inv['id'];
$countUsers = $inv['uid'];
}