diff --git a/src-db/database/model/prescript-Oracle.sql b/src-db/database/model/prescript-Oracle.sql
--- a/src-db/database/model/prescript-Oracle.sql
+++ b/src-db/database/model/prescript-Oracle.sql
@@ -210,3 +210,25 @@
    FROM DUAL
 /-- END
 
+CREATE OR REPLACE FUNCTION ADD_HOURS(p_date DATE, p_hours INTEGER) RETURN DATE
+AS
+/*************************************************************************
+* The contents of this file are subject to the Openbravo  Public  License
+* Version  1.1  (the  "License"),  being   the  Mozilla   Public  License
+* Version 1.1  with a permitted attribution clause; you may not  use this
+* file except in compliance with the License. You  may  obtain  a copy of
+* the License at http://www.openbravo.com/legal/license.html
+* Software distributed under the License  is  distributed  on  an "AS IS"
+* basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See the
+* License for the specific  language  governing  rights  and  limitations
+* under the License.
+* The Original Code is Openbravo ERP.
+* The Initial Developer of the Original Code is Openbravo SLU
+* All portions are Copyright (C) 2013 Openbravo SLU
+* All Rights Reserved.
+* Contributor(s):  ______________________________________.
+************************************************************************/
+BEGIN
+RETURN p_date + p_hours/24;
+END ADD_HOURS;
+/-- END 
diff --git a/src-db/database/model/prescript-PostgreSql.sql b/src-db/database/model/prescript-PostgreSql.sql
--- a/src-db/database/model/prescript-PostgreSql.sql
+++ b/src-db/database/model/prescript-PostgreSql.sql
@@ -539,6 +539,18 @@
 ' LANGUAGE 'plpgsql' IMMUTABLE
 /-- END
 
+CREATE OR REPLACE FUNCTION add_hours
+(
+timestamp,
+numeric
+)
+RETURNS timestamptz AS '
+BEGIN
+    return $1 + to_interval($2::INTEGER,to_char(''hours''));
+END;
+' LANGUAGE 'plpgsql' IMMUTABLE
+/-- END
+
 CREATE OR REPLACE FUNCTION add_days
 (
 timestamp with time zone,