horde, phplib, php4, mysql: problem solved

[Alexander List <alexlist@sbox.tu-graz.ac.at>]

On Tue, 18 Jul 2000, Ivan E. Moore II wrote:

> arg...your not the only one who is seeing this...it's very bizarre and I have
> not been able to figure out what's causing it.  Well, I should say, the
> one incident of it that I've seen.  Have you exited out of your browser
> and tried again?  If not, try that...if you still see the same results than
> I'm up to 2 strange occurances...

OK, on the php website I found out that mysql_affected_rows is causing
troubles anyway, so I wrote a workaround:

What do you think about this code? Could there be a problem that it's
nonatomic?

Thanks for any suggestions to improve this beast...

regards

Alex

--- ct_sql.inc.orig	Sun Apr  9 21:50:33 2000
+++ ct_sql.inc	Tue Jul 18 19:08:12 2000
@@ -8,6 +8,9 @@
 ## 
 ## $Id: ct_sql.inc,v 1.1.2.1 2000/04/09 19:50:33 chuck Exp $
 ##
+## modified by Alexander List <alexlist@sbox.tu-graz.ac.at> 2000/07/18
+## to work around MySQL problems with mysql_affected_rows (al)
+##
 ## PHPLIB Data Storage Container using a SQL database
 ##
 
@@ -71,6 +74,12 @@
     $name = addslashes($name);
 
     $now = date("YmdHis", time());
+
+    # here, we look if there's already a session open with sid/name (al)
+    $tquery = sprintf("select * from %s where sid='%s' and name='%s'",
+      $this->database_table,
+      $id,
+      $name);
     $uquery = sprintf("update %s set val='%s', changed='%s' where sid='%s' and name='%s'",
       $this->database_table,
       $str,
@@ -84,14 +93,28 @@
       $str,
       $now);
 
-    # This may look wierd, but SELECTing first and then doing the
-    # right thing would nonatomic (in MySQL, where we cannot SELECT
-    # FOR UPDATE). This is nonatomic, too, but keeps the window small.
-    $this->db->query($uquery);
-    if (  $this->db->affected_rows() == 0 
-      && !$this->db->query($iquery)) {
-        $ret = false;
+
+    # now if there's a session open, update the record, else insert a new
+    # one, if that fails, return false
+    # I know this isn't atomic, but I couldn't imagine another way
+    # working around affected_rows (al)
+    $tresult=$this->db->query($tquery);
+    if ($this->db->num_rows($tresult) <> 0) {
+      $this->db->query($uquery);
+    }
+    elseif (!$this->db->query($iquery)) {
+      $ret = false;
     }
+
+# this is the original code I left for reference (al)
+//    # This may look wierd, but SELECTing first and then doing the
+//    # right thing would nonatomic (in MySQL, where we cannot SELECT
+//    # FOR UPDATE). This is nonatomic, too, but keeps the window small.
+//    if (  $this->db->affected_rows() == 0 
+//      && !$this->db->query($iquery)) {
+//        $ret = false;
+//    }
+
     return $ret;
   }