Which SME customer consumed the least in June 2012?
June 2012 refers to yearmonth.date = '201206'
SELECT T1.CustomerID FROM customers AS T1 INNER JOIN yearmonth AS T2 ON T1.CustomerID = T2.CustomerID WHERE T2.Date = '201206' AND T1.Segment = 'SME' GROUP BY T1.CustomerID ORDER BY SUM(T2.Consumption) ASC LIMIT 1