How to change one or more selection values? If I enter a value it works. Still, if I enter two values in both input fields, it doesn't work, showing the following error.
Error updating record: There is an error in your SQL syntax; check The manual corresponding to your MariaDB server version Line 1 Syntax used near 'nat = 'saf' WHERE id = '16''
if (isset($_POST['modifica'])) {
$id = $_POST['id'];
$semaphore = false;
$sql = "UPDATE users SET ";
$fields = array('nume', 'nat', 'email', 'telefon');
foreach ($fields as $field) {
if (isset($_POST[$field]) and !empty($_POST[$field])) {
$var = ($_POST[$field]);
$sql .= $field." = '$var'";
$semaphore = true;
}
}
if ($semaphore) {
$sql .= " WHERE id = '$id'";
($sql);
}
if ($conn->query($sql) === true) {
echo "Record updated successfully";
} else {
echo "Error updating record: ".$conn->error;
}
$conn->close();
} 
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@m-eriksson 评论的实施方法：
$sql = "UPDATE users SET nume = :nume, nat = :nat, email = :email, telefon = :telefon"; $fields = array('nume', 'nat', 'email', 'telefon'); if(count($fields) > 0 ){ $this->update($sql, $fields, $con) $semaphore = true; } public function update ($sql, $fields, $con) { $update = $con->prepare($query); return $update->execute($fields); }