diff --git a/Oracle/OMOP CDM ddl - Oracle.sql b/Oracle/OMOP CDM ddl - Oracle.sql
index 3cec564..d1171a6 100644
--- a/Oracle/OMOP CDM ddl - Oracle.sql	
+++ b/Oracle/OMOP CDM ddl - Oracle.sql	
@@ -254,10 +254,8 @@ CREATE TABLE observation_period
      observation_period_id				INTEGER		NOT NULL , 
      person_id							INTEGER		NOT NULL , 
      observation_period_start_date		DATE		NOT NULL , 
-     observation_period_start_datetime		TIMESTAMP WITH TIME ZONE		NOT NULL ,
      observation_period_end_date		DATE		NOT NULL ,
-     observation_period_end_datetime		TIMESTAMP WITH TIME ZONE		NOT NULL ,
-	 period_type_concept_id				INTEGER		NOT NULL
+     period_type_concept_id				INTEGER		NOT NULL
     ) 
 ;