This is a pretty simple query which is used to locate all Clients in a specific Active Directory OU.

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 where SMS_R_System.SystemOUName = "DEV.DOMAIN.LOCAL/BUILD"

Which will return all clients in the dev.domain.local Build OU.