SRQL: Sorted Relational Query Language
R. Ramakrsihnan, D. Donjerkovic, Anirudh Ranganathan, Kevin S. Beyer, Muralidhar Krishnaprasad · 2002
A relation is an unordered collection of records. Often, however there is an underlying order (e.g., a sequence of stock prices), and users want to pose queries that reflect this order (e.g., find a weekly moving average). SQL provides no support for posing such queries. We show how a rich class of queries reflecting sort order can be naturally expressed and efficiently executed with simple extensions to SQL.