Trying to understand oci8 refcursor bits

Question

Hi
I have been using ADOdb for a while and sort of not thinking too much about it, but sort of trying to get some of the stuff. Perhaps I think too much like my old C programming daze and wonder about things that I should not. With that in mind I was reading and working through some of the examples in the underground php oracle manual and came across this example:
<?php
$c = oci_connect('hr', 'hrpwd', 'localhost/XE');
// Excute the call to the PL/SQL stored procedure
$s = oci_parse($c, "call myproc(:rc)");
$refcur = oci_new_cursor($c);
oci_bind_by_name($s, ':rc', $refcur, -1, OCI_B_CURSOR);
oci_execute($s);
// Execute and fetch from the cursor
oci_execute($refcur); // treat as a statement resource
echo "<table border='1'>\n";
while($row = oci_fetch_array($refcur, OCI_ASSOC)) {
echo "<tr>";
foreach ($row as $c) {
echo "<td>$c</td>";
echo "</tr>\n";
echo "</table>\n";
?>
and I have a few questions if someone can answer them.
$c in this example holds the "handle" to the database connection ... a kind of pointer I assume
then we store in $refcur the result of oci_new_cursor() which is called with the connection variable returned from the call to oci_connect()
strangely when I print_r ($c) I just get something like:
Resource id #1
so I wonder just what I've got there ....
the next question is what is going on in the for loop there? We say:
foreach ($row as $c)
which (as far as I know) will overwrite $c ... will this not result in us loosing our DB connection?
if so, why structure it this way? economy of variables??
I assume that this will also mean that I will not be able to make any subsequent database operations (like oci_parse a new cursor
Edited by: finophile on Sep 2, 2010 10:47 PM

Answer 1

"Handle" is Oracle's C level name for some of the data structures used inside the PHP OCI8 extension. In PHP the (roughly) equivalent name is "resource". The connection resource/handle is the data structure that holds internal state of the connection to the database that wouldn't make sense for the PHP program to know about.
The reuse of $c in this example was pointed out to me a while back. Yes it will lose PHP's access to the connection. It's not intentional. I believe I was flip-flopping on whether to use $conn or $c for the connection resource in all examples. Here I ended up with $c being used for "connection" and for "column".
The UGP&OM is out of date regarding REF CURSOR performance. See http://blogs.oracle.com/opal/2009/09/oracle_database_11gr2_enhancem.html for the current information.