Hi,
You can connect to DLP Oracle database and run the following query:
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select p.USERID,p.Name,u.AssumedRoleName,u.IPADDRESS,u.LOGONTIME,u.LOGOFFTIME
from PROTECTUSER p, USERSESSION u
where p.USERID = u.USERID
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The result will be some like this:
USERID,NAME,ASSUMEDROLENAME,IPADDRESS,LOGONTIME,LOGOFFTIME
41,"dlp-user","dlp-remediator","172.16.30.12","2012-11-09 14:23:46","2012-11-09 14:23:46"
1,"Administrator",(null),"172.16.30.2","2012-11-23 07:47:31","2012-11-23 07:49:18"
You can use the Auditlog as yang_zhang said but the Auditlog don't have the logoff information.
Hope this help...
Eduardo Barcelos