PHP中的MYSQL UPDATE和SET语句（500错误响应）[重复]

I'm a newb, so thanks in advance for bearing with me. That being said, I'm trying to update a table in my database and failing. I received a few NULL responses, adjusted a few things, and most recently got a few 500 internal server errors, which typically seem to be related to invalid PHP... any help is greatly appreciated.

if ($conn->connect_error) {
die("Connection failed: " . $conn->connect_error);
}

if ($_POST['room']) {

$room_current = $conn->query('SELECT `Room_Availability` FROM Room_Status WHERE `Room_Name` = "'.$_POST['room'].'"');

if (!$room_current) {
    die('ERROR: '.$conn->error);
}

$room_current = $room_current->fetch_assoc();

if ($room_current['Room_Availability'] == `OUT`); {
    $room_set = $conn->query('UPDATE `Room_Status` SET `Room_Availability`= `IN` WHERE `Room_Name` = "'.$_POST['room'].'"');

    if (!$room_set); {
        die('ERROR: '.$conn->error);
    }
}

var_dump($room_set);

?>

</div>

This is your UPDATE:

UPDATE `Room_Status`
    SET `Room_Availability` = `IN`
    WHERE `Room_Name` = "'.$_POST['room'].'"'

The backticks around IN mean that this is a column reference. You probably want a string, so use single quotes:

UPDATE `Room_Status`
    SET `Room_Availability` = 'IN'
    WHERE `Room_Name` = "'.$_POST['room'].'"'

just replace the

$room_set = $conn->query('UPDATE `Room_Status` SET
`Room_Availability`= `IN` WHERE `Room_Name` = "'.$_POST['room'].'"');

to

$room_set = $conn->query('UPDATE `Room_Status` SET
`Room_Availability`= 'IN' WHERE `Room_Name` = "'.$_POST['room'].'"');