SQL query doesn't give results in PHP through MySQLi

Question

I have this SQL query founded here on stackoverflow and adjusted to match my needs, that works in phpMyAdmin:

$queryClassifica = "SELECT Squadra, 
SUM( CASE WHEN PuntiCasa > PuntiTrasferta THEN 2 ELSE 0 END ) punti, 
COUNT( CASE WHEN PuntiCasa >0 AND PuntiTrasferta >0 THEN 1 END ) giocate, 
COUNT( CASE WHEN PuntiCasa > PuntiTrasferta THEN 1 END ) vinte, 
COUNT( CASE WHEN PuntiTrasferta > PuntiCasa THEN 1 END ) perse, 
SUM( PuntiCasa ) PuntiCasa, 
SUM( PuntiTrasferta ) PuntiTrasferta, 
SUM( PuntiCasa ) - SUM( PuntiTrasferta ) diff_canestri
FROM ( 
SELECT SquadraCasa Squadra, PuntiCasa, PuntiTrasferta
FROM calendario
UNION ALL 
SELECT SquadraTrasferta, PuntiTrasferta, PuntiCasa
FROM calendario
)a
GROUP BY Squadra
ORDER BY Punti DESC , diff_canestri DESC";

In my PHP page I submit the same query, but it doesn't work, if I check the rows number it's always 0.

$result = mysqli_query($con, $queryClassifica);
$row_cnt = $result->num_rows;

And of course, if I fetch the result of the query, the array is empty. Where's the mistake?

Answer 1

It looks like you're combining both object orientated style as well as procedural style. If your code is written in object orientated style:

$result = $mysqli->query($queryClassifica);
$row_cnt = $result->num_rows;

$result->close();
$mysqli->close();

or procedural style:

$result = mysqli_query($link,$queryClassifica);
$row_cnt = mysqli_num_rows($result);

mysqli_free_result($result);
mysqli_close($link);

I'd say that you've most likely written it procedural however try both.