Have you heard about the Lateral join? In short - lateral join or lateral correlation is simply a reference in a nested table expression to a column of a table identified at the same level in the FROM clause. Learn the basics in this article.
This article series discuss the major Db2 temporal enhancements delivered in Db2 12 for z/OS and Db2 for z/OS Continuous Delivery (CD), e.g., temporal logical transaction, temporal RI, and replication and temporal query enhancements on temporal auditing.
Db2 12 SQL Pagination: The ability to "page" through a result set and see the next "page" of results. Db2 12 introduced support for data-dependent and numeric-based pagination.
With the SQL OLAP RANK and DENSE_RANK functions being around for a while in SQL programming, it is quite easy to query for the TOP XX from data.
Thinking about using SQL to analyze data residing in Hadoop? Take a look at a brief comparison of Hive and IBM Big SQL.