Operations with timestamp (query sql)

Operations with timestamp (query sql)

In proc sql for SAS I have this query to calculate TIME_FOR_REPLY
(operations with timestamp).
SELECT
(CASE
WHEN Wcs_dashboard_interaction.END_TIMESTAMP is null AND
Wcs_dashboard_interaction.DISPATCH_TIMESTAMP IS NULL AND
Wcs_dashboard_interaction.START_TIMESTAMP IS NOT NULL THEN
(MAX(Wcs_dashboard_session.END_TIMESTAMP) -
MIN(Wcs_dashboard_session.START_TIMESTAMP))
WHEN Wcs_dashboard_interaction.END_TIMESTAMP is null AND
Wcs_dashboard_interaction.DISPATCH_TIMESTAMP IS NULL AND
Wcs_dashboard_interaction.START_TIMESTAMP IS NULL THEN
(MAX(Wcs_dashboard_session.END_TIMESTAMP) -
MIN(Wcs_dashboard_session.START_TIMESTAMP))
WHEN Wcs_dashboard_interaction.END_TIMESTAMP is NOT null AND
Wcs_dashboard_interaction.DISPATCH_TIMESTAMP IS NOT NULL THEN
(MAX(Wcs_dashboard_interaction.DISPATCH_TIMESTAMP) -
MIN(Wcs_dashboard_session.START_TIMESTAMP))
WHEN Wcs_dashboard_interaction.END_TIMESTAMP is null AND
Wcs_dashboard_interaction.DISPATCH_TIMESTAMP IS NOT NULL THEN
(MAX(Wcs_dashboard_interaction.DISPATCH_TIMESTAMP) -
MIN(Wcs_dashboard_session.START_TIMESTAMP))
WHEN Wcs_dashboard_interaction.END_TIMESTAMP is NOT null AND
Wcs_dashboard_interaction.DISPATCH_TIMESTAMP IS NULL THEN
(MAX(Wcs_dashboard_session.END_TIMESTAMP) -
MIN(Wcs_dashboard_session.START_TIMESTAMP))
ELSE '00.00.00't
END) AS TIME_FOR_REPLY
FROM UNIBANK_ASYNC.Wcs_dashboard_session Wcs_dashboard_session
LEFT JOIN UNIBANK_ASYNC.Wcs_dashboard_interaction
Wcs_dashboard_interaction ON
Wcs_dashboard_session.WCS_SESSION_ID=Wcs_dashboard_interaction.WCS_SESSION_ID
LEFT JOIN UNIBANK_ASYNC.Wcs_dashboard_escalation Wcs_dashboard_escalation
ON
Wcs_dashboard_session.WCS_SESSION_ID=Wcs_dashboard_interaction.WCS_SESSION_ID
LEFT JOIN UNIBANK_ASYNC.Wcs_dashboard_hold_resume
Wcs_dashboard_hold_resume ON
Wcs_dashboard_session.WCS_SESSION_ID=Wcs_dashboard_hold_resume.WCS_SESSION_ID
LEFT JOIN UNIBANK_ASYNC.Wcs_dashboard_share Wcs_dashboard_share ON
Wcs_dashboard_session.WCS_SESSION_ID=Wcs_dashboard_share.WCS_SESSION_ID
LEFT JOIN UNIBANK_ASYNC.Wcs_survey Wcs_survey ON
Wcs_survey.EXTERNAL_ID=Wcs_dashboard_session.EXTERNAL_ID
When I create the query in iReport I don't know what is the correct
syntax: '00.00.00't (I would like that as a last case statement were
enhanced by the timestamp "00:00:00")
This is the format of the columns 2013-08-07 17:55:49.223
(Wcs_dashboard_interaction.END_TIMESTAMP, ecc....)
Can you give me some help?