Table: airbender_season2_dvd
Columns: volume
discs
episodes
region_1_release
region_2_release
region_4_release

Question: What is the region 4 release that has july 20, 2009 as the region 2?
SQL: SELECT "region_4_release" FROM airbender_season2_dvd WHERE "region_2_release" = 'july 20, 2009'

Question: What is the region 1 release that has july 20, 2009 as the region 2?
SQL: SELECT "region_1_release" FROM airbender_season2_dvd WHERE "region_2_release" = 'july 20, 2009'

Question: What is the average episode that has September 11, 2007 as a region 1?
SQL: SELECT AVG("episodes") FROM airbender_season2_dvd WHERE "region_1_release" = 'september 11, 2007'