SQL syntax error IN - php

Question

I'm writing a script to figure out whether changes have been made to my data.
However i'm getting this error:
Error: UPDATE Workhours SET IN= '07:59' WHERE AFNumber='AF1585' AND
Date='09/07/2015' 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 'IN= '07:59' WHERE AFNumber='AF1585' AND
Date='09/07/2015'' at line 1Error: UPDATE Workhours SET OUT= '14:04'
WHERE AFNumber='AF1585' AND Date='09/07/2015'
Any help please?
if (isset($_POST['submit']))
{
$sql = "SHOW COLUMNS FROM Workhours";
$result = mysqli_query($con,$sql);
while($row = mysqli_fetch_array($result)){
$tempname = $row['Field'];
$sql2 = "UPDATE Workhours SET ".$row['Field']."= '$_POST[$tempname]' WHERE AFNumber='".$_GET["af"]."' AND Date='".$_GET["date"]."'";
$result2 = mysqli_query($con,$sql2);
if ($con->query($sql2) === TRUE) {
} else {
echo "Error: " . $sql2 . "<br>" . $con->error;
}
}
$sql3 = "SELECT * FROM Workhours WHERE AFNumber='".$_GET["af"]."' AND (".$row['Field']." NOT LIKE '".$_POST[$tempname]."')";
$result3 = mysqli_query($con,$sql3);
if (mysqli_num_rows($result3) > 0) {
// output data of each row
while($row3 = mysqli_fetch_array($result3)) {
$sql3 = "INSERT INTO `Changes` (`Table`, `AFNumber`, `Attribute`, `DateChanged`, `HRUser`, `OldValue`, `NewValue`)
VALUES ('Workhours', '".$_GET["af"]."', '".$row["Field"]."', '".date('dd/m/Y HH:mm:ss')."', '$login_session', '', '$_POST[$tempname]')";
if (mysqli_query($con,$sql3) === TRUE) {
} else {
echo "Error: " . $sql3 . "<br>" . mysqli_error($con);
}
}
}
echo '<script>swal("Success", "Changes have been saved", "success");</script>';
}

Answer 1

IN and OUT are keywords in MySQL. You have to escape the $row['Field'] with backticks.
$sql2 = "UPDATE Workhours SET `".$row['Field']."`= '$_POST[$tempname]' WHERE AFNumber='".$_GET["af"]."' AND Date='".$_GET["date"]."'";
Also you should use prepared statements for preventing SQL injection.