Tell me the publication date of the book﻿Dead Corps.
select t2.publication_date from book as t1 join publication as t2 on t1.book_id = t2.book_id where t1.title = "Dead Corps"
How about the book Cyberella?
select t2.publication_date from book as t1 join publication as t2 on t1.book_id = t2.book_id where t1.title = "Cyberella"
Okay, please show me the most common publication date.
select publication_date from publication group by publication_date order by count(*) desc limit 1