if($id == 1){ // deleting first row
mysqli_query($db,"UPDATE employees SET id=id-1 WHERE id>1");
}
else if($id>1 && $id<$num){ // deleting middle row
mysqli_query($db,"UPDATE employees SET id=id-1 WHERE id>$id");
}
else if($id == $num){ // deleting last row
mysqli_query($db,"ALTER TABLE employees AUTO_INCREMENT = $num");
}
else{
echo "ERROR";
}
mysqli_query($db,"ALTER TABLE employees AUTO_INCREMENT = $num");