Conversion of date datatype to timestamp in OBIEE

Hi,
In OBIEE, direct date to timestamp conversion is not possible unless we use evaluate functions to call it’s database functions…
One way i found to convert date column to it’s timestamp is:
First, cast the date column to char later cast it to timestamp
Ex: Cast(Cast(CURRENT_DATE AS CHAR) AS TIMESTAMP)
 
You may have question why we need to convert it to timestamp..
Well, while using timestampdiff with sql_tsi_hour as interval, we can’t pass date datatype columns as it throws error:
Ex: TimestamDiff(SQL_TSI_HOUR, TimeID, CURRENT_DATE) won’t take as functionality. Gives you following error:

[nQSError: 10058] A general error has occurred. [nQSError: 22025] Function TimestampDiff is called with an incompatible type. (HY000)

 Now, try in this way:
TimestamDiff(SQL_TSI_HOUR, TimeID, Cast(Cast(CURRENT_DATE as Char) as Timestamp))
It gives you proper results with out any error.