diff --git a/library/adodb/drivers/adodb-oci8.inc.php b/library/adodb/drivers/adodb-oci8.inc.php
index 0d69b75..ad69860 100644
--- a/library/adodb/drivers/adodb-oci8.inc.php
+++ b/library/adodb/drivers/adodb-oci8.inc.php
@@ -364,6 +364,14 @@ NATSOFT.DOMAIN =
 
 		$false = false;
 		$rs = $this->Execute(sprintf("SELECT * FROM ALL_CONSTRAINTS WHERE UPPER(TABLE_NAME)='%s' AND CONSTRAINT_TYPE='P'",$table));
+
+		if (!is_object($rs)) {
+			if (isset($savem))
+				$this->SetFetchMode($savem);
+			$ADODB_FETCH_MODE = $save;
+			return $false;
+		}
+
 		if ($row = $rs->FetchRow())
 		   $primary_key = $row[1]; //constraint_name