Old data gets wiped from POST when I use GET

Old data gets wiped from POST when I use GET

So I am having an issue. I used POST to send data to a new page. I use get
to send data to a function but it seems the POST data get wiped. Here some
code to help explain.
POST CODE to send to form vieworder (works perfect!)
<form method="post" action="vieworder.php">
<input type="hidden" name ="user_id" value="<?php echo
$_SESSION['user_id']; ?>">
<input type="hidden" name ="id" value="<?php echo $data1[$x]['id']; ?>">
<input type="submit" name="submit" value="View"> </td>
</form>
So on the vieworder page I want used to be able to update the data using
this form. This form works as well except i need that value "id" from the
orginal post. It works and the "id"has the data until I use this form.
<form name="approveform" method="get" action="">
Index Number*: <input type="text" name="IndexNum">&nbsp;
<input type="submit" value="Approve" action="">
</form>
I would also prefer to use the POST method but using GET was my first
solution to no deleting the data from POST.
Anyways I then just send the data to a function to update two fields.
Any way to get correct the code?