$re=mysql_query(
"select * from productos where id=".$_GET['id']
)
or die (mysql_error());
This upper line gives me this error, but I can not find it:
You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '' at line 1
Your code has several problems:
die() instead of exceptions However, all that goes on the side of good practices. Assuming that you do not intend to change your practices, the specific error can be debugged by doing:
$sentencia="select * from productos where id=".$_GET['id'];
print_r($sentencia);
$re=mysql_query($sentencia) or die (mysql_error());
That does not solve your problem, but it is the way for you to diagnose yourself what you are going to mysql_query instead of simply assume that "you can not find the error".
Recommendation
Do not use the php_mysql connector. Use PDO or MySQLi. Use prepared statements instead of direct interpolation of variables. Check the existence of a superglobal instead of using it directly. Use exceptions instead of die() .
How would it look like with PDO:
if(!isset($_GET['id']) ){ // <-- compruebo la existencia de la superglobal
echo 'No está fijado el parámetro "id"';
} else {
$id = $_GET['id'];
$sentencia="select * from productos where id=:id";
$stmt = $conn->prepare($sentencia); // <-- uso una sentencia preparada
try {
$stmt->execute([':id'=>$id]); // <-- PDO sanitiza el parámetro $id
} catch (\PDOException $e) {
echo 'Ocurrió un error en la consulta: '.$e->getMessage();
}
}