I've found this script on Venu Singireddy's blog: SCCM Collection query for machines not rebooted in last 30 days
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_OPERATING_SYSTEM on SMS_G_System_OPERATING_SYSTEM.ResourceID = SMS_R_System.ResourceId where (SMS_G_System_OPERATING_SYSTEM.Caption like "%xp%" or SMS_G_System_OPERATING_SYSTEM.Caption like "%vista%" or SMS_G_System_OPERATING_SYSTEM.Caption like "%windows 7%") and (DateDiff(day, SMS_G_System_OPERATING_SYSTEM.LastBootUpTime, GetDate()) >30)
Where do insert it? I am completely new to sccm 2012.