The MySQL update query does not work

I have mysql table with following fields

id (which auto increments)

title,name,age,institution,iod

the fields like title,name,age,institution are entered in the form structure (html page) and by clicking submit button are stored in DB(mysql)

iod is the field is something like this 123/id (nothing but same id field but with '123/' prefix before)

now when the user enters title,name,age,institution these need to stored in DB including id and iod.

Now for executing the above i wrote the following the fields title,name,age,institution and id are successfully stored but iod is not stored.

Can you please show me the error i made here??

I wrote the following syntax for the code(part of the same code)

if ($_POST['title'] != '')
{
$value = $_POST['title'];
$value1 = $_POST['name'];
$value2 = $_POST['age'];
$value5 = $_POST['institution']; 

$sql = "INSERT INTO parentid(title,name,age,institution) VALUES('$value','$value1','$value2','$value5')"  ;

}
$sql1="SELECT * FROM parentid ORDER BY id DESC LIMIT 1";
$value6=$row['id'];
$value4= '123/' . $row['id'] ;
$sql2="UPDATE parentid SET iod='$value4' WHERE id = '$value6' ";

---

The problem is that you are not executing your queries, you just put the query in a string but then you don´t do anything with it.

For the second query (simple sample code):

$sql1="SELECT * FROM parentid ORDER BY id DESC LIMIT 1";
$result = mysql_query($sql1);
if ($row = mysql_fetch_assoc($result))
{
  $value6=$row['id'];
  // etc., error handling not added
}