Fixed a warning

ChangeLog

@@ -14,6 +14,7 @@ $Source$
 	* db_details.php3, tbl_change.php3, tbl_properties.php3, user_details.php3:
 	  xhtml fixes.
 	* lang/slovak-win1250.inc.php3: updated thanks to Peter Svec.
+    * tbl_qbe.php3, line 732: fixed again a warning.
 
 2002-04-27 Marc Delisle  <lem9@users.sourceforge.net>
     * tbl_properties.php3, new tbl_properties_links.php3:

tbl_qbe.php3

@@ -729,7 +729,7 @@ if (isset($Field) && count($Field) > 0) {
             $wtable = explode('.', $curField[$x]);
             $ctable = str_replace('`', '', $wtable[0]);
             if (!empty($curField[$x]) && !empty($curCriteria[$x])) {
-                if ($where[$ctable] != '=') {
+                if (isset($where[$ctable]) && $where[$ctable] != '=') {
                     $where[$ctable] = substr($curCriteria[$x], 0, 1);
                 }
             }