What was the dew point on the day the most units of item no.5 were sold in store no.3 in 2012?
item no. 5 refers to item_nbr = 5; store no.3 refers to store_nbr = 3; in 2012 refers to SUBSTR(date, 1, 4) = '2012': most units sold refers to Max(units)
SELECT dewpoint FROM sales_in_weather AS T1 INNER JOIN relation AS T2 ON T1.store_nbr = T2.store_nbr INNER JOIN weather AS T3 ON T2.station_nbr = T3.station_nbr WHERE T2.store_nbr = 3 AND SUBSTR(T1.`date`, 1, 4) = '2012' AND T1.item_nbr = 5 ORDER BY units DESC LIMIT 1
database name:db_id sales_in_weather
sales_in_weather table sales_in_weather Cols: date dtype date, store number dtype integer, item number dtype integer, units dtype integer, 
weather table weather Cols: station number dtype integer, date dtype date, temperature max dtype integer, temperature min dtype integer, temperature average dtype integer, departure from normal dtype integer, dew point dtype integer, wet bulb dtype integer, heat dtype integer, cool dtype integer, sunrise dtype text, sunset dtype text, code summarization dtype text, snowfall dtype real, preciptotal dtype real, station pressure dtype real, sea level dtype real, resultant speed dtype real, resultant direction dtype integer, average speed dtype real, 
relation table relation Cols: store number dtype integer, station number dtype integer, 
