Computer 1 Group A
Computer 2 Group B
Computer 3 Group A+B
Computer 4 Group A+B
select SMS_R_SYSTEM.ResourceID,SMS_R_SYSTEM.ResourceType,SMS_R_SYSTEM.Name,SMS_R_SYSTEM.SMSUniqueIdentifier,SMS_R_SYSTEM.ResourceDomainORWorkgroup,SMS_R_SYSTEM.Client from SMS_R_System inner join SMS_G_System_COMPUTER_SYSTEM on SMS_G_System_COMPUTER_SYSTEM.ResourceID = SMS_R_System.ResourceId where SMS_G_System_COMPUTER_SYSTEM.Name not in (select distinct SMS_G_System_COMPUTER_SYSTEM.Name from SMS_R_System inner join SMS_G_System_COMPUTER_SYSTEM on SMS_G_System_COMPUTER_SYSTEM.ResourceID = SMS_R_System.ResourceId where SMS_R_System.SystemOUName = "Group B" ) and SMS_R_System.SystemOUName = "Group A"
Cross link on my blog to other exclusions
http://sms-hints-tricks.blogspot.com/2007/10/excluding-computers-from-collection.html
