Index: branches/unlabeled/unlabeled-1.30.2/core/kernel/db/dbitem.php
===================================================================
diff -u -r7649 -r7725
--- branches/unlabeled/unlabeled-1.30.2/core/kernel/db/dbitem.php	(.../dbitem.php)	(revision 7649)
+++ branches/unlabeled/unlabeled-1.30.2/core/kernel/db/dbitem.php	(.../dbitem.php)	(revision 7725)
@@ -538,8 +538,14 @@
 			array_push($unique_fields,$field);
 			foreach($unique_fields as $unique_field)
 			{
-				$where[] = '`'.$unique_field.'` = '.$this->Conn->qstr( $this->GetDBField($unique_field) );
+				// if field is not empty or if it is required - we add where condition
+				if ($this->GetDBField($unique_field) != '' || $this->Fields[$unique_field]['required']) {
+					$where[] = '`'.$unique_field.'` = '.$this->Conn->qstr( $this->GetDBField($unique_field) );
+				}
 			}
+			// This can ONLY happen if all unique fields are empty and not required.
+			// In such case we return true, because if unique field is not required there may be numerous empty values
+			if (!$where) return true;
 
 			$sql = 'SELECT COUNT(*) FROM %s WHERE ('.implode(') AND (',$where).') AND ('.$this->IDField.' <> '.(int)$this->ID.')';