Here is a query that will create a collection of computers that have not been seen in 60 days .
This will work in both SCCM and SMS. If the computer has not been inventoried in 60 days or more then it will be placed in this collection.
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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 SMS_R_System.Name from SMS_R_System inner join SMS_G_System_WORKSTATION_STATUS on SMS_G_System_WORKSTATION_STATUS.ResourceID = SMS_R_System.ResourceId where SMS_G_System_WORKSTATION_STATUS.LastHardwareScan >= DateAdd(dd,-60,GetDate()) )
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