Table: superman_appearances
Columns: character_s
first_appearance
cover_date
publisher
estimated_value

Question: Which character first appeared in Amazing Fantasy #15?
SQL: SELECT "character_s" FROM superman_appearances WHERE "first_appearance" = 'amazing fantasy #15'

Question: What is Action Comics #1's estimated value?
SQL: SELECT "estimated_value" FROM superman_appearances WHERE "first_appearance" = 'action comics #1'

Question: Who publishes Wolverine?
SQL: SELECT "publisher" FROM superman_appearances WHERE "character_s" = 'wolverine'