MySQL查询GROUP在控制台中工作，在PHP脚本中不起作用

Question

I created a function with this mysqli query but for some reason it does not print the desired result in php script. What am I doing wrong?

SELECT  COUNT(*)
FROM (
SELECT id
FROM personal WHERE structure = ?
WHERE id IN 
(SELECT id FROM presence WHERE service = 'shift1' AND year = ? AND month = ? AND day = ? ) 
AND id IN 
(SELECT id FROM qualification WHERE idqualification = '1' or idqualification = '2')
ORDER BY RAND()
) t
GROUP BY t.id

update: this is my function. It should find persons working in a day having those qualifications and count them

function presence_by_qualification($structure, $day, $month, $year)
{
global $connection;
$stmt = $connection->prepare("SELECT  COUNT(*)
FROM (
SELECT id
FROM personal WHERE structure = ?
WHERE id IN 
(SELECT id FROM presence WHERE service = 'shift1' AND year = ? AND month = ? AND day = ? ) 
AND id IN 
(SELECT id FROM qualification WHERE idqualification = '1' or idqualification = '2')
ORDER BY RAND()
) t
GROUP BY t.id");
$stmt->bind_param('ssss', $structure, $day, $month, $year);
$stmt->execute();
$stmt->store_result();
$stmt->bind_result($counts);
results = $stmt -> fetch();
return $results;
}

I store the result in an array so I can count them.

$presencebyqualif[] = presence_by_qualification($structure, $day, $month, $year);

I am using it like this:

$structure = "1029";
$day = "01";
$month = "05";
$year = "2019";

They are all variables. It should show the counted number of people on shift having these specific qualifications.

Answer 1

You placed wrong order of params in bind_param() function. You should add params value in order of "?" you used in your query. Please do following changes:

$stmt->bind_param('ssss', $structure, $year, $month, $day);

Hope it may helpful to you!!