Table: last_of_summer_wine
Columns: series_number
number_of_episodes
original_air_date
dvd_region_2_release_date
dvd_region_1_release_date

Question: How many series originally aired before 1999 with more than 7 episodes and a DVD Region 1 release date of 16 april 2013?
SQL: SELECT COUNT("series_number") FROM last_of_summer_wine WHERE "original_air_date" < 1999 AND "number_of_episodes" > 7 AND "dvd_region_1_release_date" = '16 april 2013'

Question: What's the latest original air date with more than 10 episodes and a DVD Region 2 release date of 23 april 2012?
SQL: SELECT MAX("original_air_date") FROM last_of_summer_wine WHERE "dvd_region_2_release_date" = '23 april 2012' AND "number_of_episodes" > 10

Question: What was the original air date of series number 10?
SQL: SELECT AVG("original_air_date") FROM last_of_summer_wine WHERE "series_number" = 10

Question: What's the sum of the number of episodes that originally aired after 1991 with a series number smaller than 21 and a DVD Region 2 release date of 26 march 2012?
SQL: SELECT SUM("number_of_episodes") FROM last_of_summer_wine WHERE "original_air_date" > 1991 AND "series_number" < 21 AND "dvd_region_2_release_date" = '26 march 2012'

Question: What's the lowest series number that originally aired before 2009 with more than 7 episodes and had a DVD Region 2 release date of 26 july 2004?
SQL: SELECT MIN("series_number") FROM last_of_summer_wine WHERE "original_air_date" < 2009 AND "dvd_region_2_release_date" = '26 july 2004' AND "number_of_episodes" > 7