This document is intended as a reference guide to the full syntax and semantics of the SQL++ Query Language, a SQL-inspired language for working with semistructured data. SQL++ has much in common with SQL, but there are also differences due to the data model that the language is designed to serve. (SQL was designed in the 1970's for interacting with the flat, schema-ified world of relational databases, while SQL++ is designed for the nested, schema-less/schema-optional world of modern NoSQL systems.) In particular, SQL++ in the context of Apache AsterixDB is intended for working with the Asterix Data Model (ADM), which is a data model aimed at a superset of JSON with an enriched and flexible type system.
New AsterixDB users are encouraged to read and work through the (friendlier) guide "AsterixDB 101: An ADM and SQL++ Primer" before attempting to make use of this document. In addition, readers are advised to read and understand the Asterix Data Model (ADM) reference guide since a basic understanding of ADM concepts is a prerequisite to understanding SQL++. In what follows, we detail the features of the SQL++ language in a grammar-guided manner: we list and briefly explain each of the productions in the SQL++ grammar, offering examples (and results) for clarity.