Database: sales_in_weather
Question: Give the station pressure status recorded by the weather station which contained no.12 store on 2012/5/15.
SQL: SELECT T1.stnpressure FROM weather AS T1 INNER JOIN relation AS T2 ON T1.station_nbr = T2.station_nbr WHERE T1.`date` = '2012-05-15' AND T2.store_nbr = 12